Solid titanium catalyst component for ethylene polymerization, ethylene polymerization catalyst and ethylene polymerization method

ABSTRACT

Provided are a solid titanium catalyst component for ethylene polymerization which can polymerize ethylene at a high activity and which can provide an ethylene polymer having an excellent particle property, an ethylene polymerization catalyst and an ethylene polymerization method in which the catalyst is used. 
     The solid titanium catalyst component (I) for ethylene polymerization according to the present invention is obtained by bringing a liquid magnesium compound (A) including a magnesium compound, an electron donor (a) having 1 to 5 carbon atoms and an electron donor (b) having 6 to 30 carbon atoms into contact with a liquid titanium compound (C) under the presence of an electron donor (B) and includes titanium, magnesium and a halogen. The ethylene polymerization catalyst of the present invention includes the component (I) and an organic metal compound catalyst component (II). Further, the ethylene polymerization method of the present invention is a method for polymerizing ethylene under the presence of the catalyst.

FIELD OF THE INVENTION

The present invention relates to a solid titanium catalyst component forethylene polymerization, an ethylene polymerization catalyst and anethylene polymerization method, each of which provides an ethylenepolymer having less solvent-soluble components and a good particleproperty at a very high activity and each of which is excellent in amolecular weight-controlling performance.

BACKGROUND OF THE INVENTION

Ethylene polymers such as homopolyethylene and linear low densitypolyethylene (LLDPE) are excellent in a transparency, a mechanicalstrength and the like and widely used as a film and the like. Variousproduction methods for the ethylene polymers have so far been known, andit is known that use of a solid titanium catalyst comprising a titaniumcatalyst component containing titanium, magnesium, a halogen and anelectron donor as an optional component makes it possible to produceethylene polymers at a high polymerization activity. In particular, itis described in a patent document 1 that a catalyst for ethylenepolymerization comprising as a titanium catalyst component, a solidtitanium catalyst component obtained by bringing a halogen-containingmagnesium compound prepared in a liquid state into contact with a liquidtitanium compound and an organic silicon compound having no activehydrogens shows a high activity. Further, it is described in a patentdocument 2 that polymers having excellent particle properties areproduced by using an olefin polymerization catalyst comprising analuminum compound selected from aluminosiloxane, a reaction product ofalkylaluminum and calixarene and a reaction product of alkylaluminum andcyclodextrin, a halogen-containing magnesium compound and a titaniumcompound.

On the other hand, if ethylene can be polymerized at a higher activityin producing the ethylene polymers, not only the productivity isimproved, but also a catalyst residue per polymer, particularly ahalogen amount is reduced, and therefore problems such as generation ofrust on a die in molding can be resolved. Accordingly, a titaniumcatalyst component which can polymerize ethylene at a higher activity isdesired.

Polymers obtained by polymerizing ethylene are usually obtained in apowder form regardless of a slurry method, a gas phase method and thelike. In this case, they are preferably ethylene polymers which do notcontain fine powders and have a narrow particle size distribution andwhich are excellent in a particle flowability. The ethylene polymerswhich are excellent in particle properties have various advantages thatthey can be used as they are without pelletizing depending on uses.

Further, known is a method in which a molecular weight distribution isbroadened by multistage polymerization in order to obtain a film whichis excellent in a transparency and a mechanical strength. Usually, amolecular weight is controlled by adding hydrogen, but the activitytends to be reduced when elevating an amount of hydrogen to produce alow molecular weight part. That is, a catalyst which can control amolecular weight with a small amount of hydrogen is advantageous interms of an activity even in multistage polymerization. Accordingly, anethylene polymerization catalyst having an excellent property ofcontrolling a molecular weight by hydrogen, which is called a hydrogenresponse, is desired.

Also, a polymerization solvent-soluble component tends to be increasedwhen producing a low molecular weight part by multistage polymerization,and by product comprising the soluble component is desired to be reducedfor the sake of a yield of the product and environmental correspondence.

-   Patent document 1: JP 1997-328514A-   Patent document 2: JP 1998-53612A

DISCLOSURE OF THE INVENTION

In light of the background described above, an object of the presentinvention is to provide a solid titanium catalyst component for ethylenepolymerization which can polymerize ethylene at a high activity, whichis excellent in a hydrogen response, which by-produces lesssolvent-soluble component and which can produce an ethylene polymerhaving a good particle property, an ethylene polymerization catalyst andan ethylene polymerization method in which the catalyst is used.

The present inventors have investigated the problems in order to solvethem. As a result, they have found, to be surprised, that a solidtitanium catalyst component (I) for ethylene polymerization obtained bybringing a liquid magnesium compound (A) comprising a magnesium compoundand two or more kinds of electron donors having a specific number ofcarbon atoms into contact with a liquid titanium compound (C) under thepresence of an electron donor (B) can solve the problems, and thus theyhave completed the present invention.

That is, the present invention provides: a solid titanium catalystcomponent (I) for ethylene polymerization, which is obtained by bringinga liquid magnesium compound (A) comprising a magnesium compound, anelectron donor (a) having 1 to 5 carbon atoms and an electron donor (b)having 6 to 30 carbon atoms into contact with a liquid titanium compound(C) under the presence of an electron donor (B) and which comprisestitanium, magnesium and a halogen.

The molar ratio ((a)/(b)) of the used amount of the electron donor (a)to the used amount of the electron donor (b) is preferably less than 1,and the electron donor (a), the electron donor (b) and the electrondonor (B) are preferably hetero atom-containing compounds excludingcyclic ether compounds.

The electron donor (a) is preferably an alcohol having 1 to 5 carbonatoms, and the electron donor (b) is preferably an alcohol having 6 to12 carbon atoms.

The electron donor (B) is preferably a dicarboxylic ester compound or atleast one compound selected from the group consisting of acid halides,acid amides, nitriles, acid anhydrides, organic acid esters andpolyethers.

More preferred aspects of the electron donor (3) include a compoundrepresented by the following Formula (2), a diether compound representedby the following Formula (3) or a mixture of an organic acid esterhaving 2 to 18 carbon atoms and the diether compound represented by thefollowing Formula (3).

In Formula (2), C^(a) and C^(b) represent a carbon atom; n represents aninteger of 5 to 10; R² and R³ each are independently COOR¹ or R′, and atleast one of R² and R³ is COOR¹; in a cyclic framework, anycarbon-carbon bond other than a C^(a)-C^(a) bond and a C^(a)-C^(b) bondwhen R³ is a hydrogen atom may be substituted with a double bond.

A plurality of R¹ is a hydrocarbon group having 1 to 20 carbon atoms.

A plurality of R′ each is independently an atom or a group selected froma hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, ahalogen atom, a nitrogen-containing group, an oxygen-containing group, aphosphorus-containing group, a halogen-containing group and asilicon-containing group.

A is a structure represented by the following formula or a hetero atomexcluding an oxygen atom:

A plurality of R′ is the same as R′ described above.

In Formula (3), m represents an integer of 1 to 10; R¹¹, R¹² and R³¹ toR³⁶ each are independently a hydrogen atom or a substituent having atleast one element selected from carbon, hydrogen, oxygen, fluorine,chlorine, bromine, iodine, nitrogen, sulfur, phosphorus, boron andsilicon.

Any ones of R¹¹, R¹² and R³¹ to R³⁶ may be linked together to form aring other than a benzene ring, and a main chain may contain an atomother than carbon.

The ethylene polymerization catalyst of the present invention ischaracterized by comprising the solid titanium catalyst component (I)for ethylene polymerization and an organic metal compound catalystcomponent (II).

The ethylene polymerization method of the present invention ischaracterized by homopolymerizing ethylene or copolymerizing ethylenewith other olefins under the presence of the ethylene polymerizationcatalyst.

ADVANTAGEOUS OF THE INVENTION

The solid titanium catalyst component for ethylene polymerization, theethylene polymerization catalyst and the ethylene polymerization methodaccording to the present invention make it possible to produce anethylene polymer which contains less solvent-soluble components andwhich is excellent in a particle form with an excellent hydrogenresponse at a high activity. Further, they are excellent in controllinga molecular weight and a molecular weight distribution of the ethylenepolymer obtained.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a graph showing relation between a intrinsic viscosity [η] anda solvent-soluble component rate out of the results of ethylenepolymerization described in the examples and the comparative examples.

PREFERRED EMBODIMENT OF THE INVENTION

The solid titanium catalyst component (I) for ethylene polymerization,the ethylene polymerization catalyst comprising the catalyst component(I) and the ethylene polymerization method according to the presentinvention shall be explained below. In the present invention, the termof “polymerization” may be used in the meaning that it includes not onlyhomopolymerization but also copolymerization, and the term of “polymer”may be used in the meaning that it includes not only a homopolymer butalso a copolymer.

<Solid Titanium Catalyst Component (I) for Ethylene Polymerization>

The solid titanium catalyst component (I) for ethylene polymerizationaccording to the present invention is obtained by bringing the liquidmagnesium compound (A) comprising the magnesium compound, the electrondonor (a) and the electron donor (b) into contact with the liquidtitanium compound (C) under the presence of the electron donor (B) andcomprises titanium, magnesium and a halogen. The solid titanium catalystcomponent (I) for ethylene polymerization obtained by bringing theliquid magnesium compound (A) into contact with the liquid titaniumcompound (C) under the presence of the electron donor (B) is excellentin a hydrogen response, produces less solvent-soluble components, andtends to be liable to provide an ethylene polymer which is excellent ina particle form. The liquid magnesium compound (A), the electron donor(B) and the liquid titanium compound (C) shall be explained below.

Liquid Magnesium Compound (A):

Representative examples of a method for obtaining the liquid magnesiumcompound (A) used for preparing the solid titanium catalyst component(I) for ethylene polymerization according to the present inventioninclude a method bringing a publicly known magnesium compound intocontact with the electron donor (a) and the electron donor (b) eachdescribed later preferably under the presence of a liquid hydrocarbonmedium to turn them into a liquid. The magnesium compounds include, forexample, magnesium compounds described in Japanese Patent ApplicationLaid-Open No. 83006/1983 and Japanese Patent Application Laid-Open No.811/1981. In particular, solvent-soluble magnesium compounds arepreferably used.

To be specific, capable of being used are publicly known magnesiumcompounds having no reducing ability, including:

-   magnesium halides such as magnesium chloride and magnesium bromide;-   alkoxymagnesium halides such as methoxymagnesium chloride and    ethoxymagnesium chloride;-   aryloxymagnesium halides such as phenoxymagnesium chloride;-   alkoxymagnesiums such as ethoxymagnesium, isopropoxymagnesium,    butoxymagnesium and 2-ethylhexoxymagnesium;-   aryloxymagnesiums such as phenoxymagnesium;-   carboxylates of magnesium such as magnesium stearate.

On the other hand, organic magnesium compounds and organic magnesiumhalide compounds represented by Grignard reagents can be used as well.

The magnesium compounds may be used alone or in combination of two ormore kinds thereof. Further, the magnesium compounds may be complexcompounds with other metals, double compounds or mixtures thereof withother metal compounds.

Among them, magnesium halides, particularly magnesium chloride ispreferably used, and in addition thereto, alkoxymagnesium such asethoxymagnesium is preferably used as well. Further, organic magnesiumcompounds having a reducing ability such as Grignard reagents, which arebrought into contact with titanium halides, silicon halides and alcoholhalides, may be used.

Two or more kinds of the electron donors used for preparing the liquidmagnesium compound (A) are preferably the electron donor (a) having 1 to5 carbon atoms and the electron donor (b) having 6 to 30 carbon atoms.To be specific, alcohols, aldehydes, amines, carboxylic acids andmixtures thereof each satisfying the respective prescribed carbon atomnumbers are preferably used.

The following compounds can be listed as the specific examples of theelectron donor (a).

The alcohols are preferably alcohols having 1 to 5 carbon atoms andinclude, for example, methanol, ethanol, n-propanol, isopropanol,n-butanol, isobutanol, ethylene glycol and n-pentanol. Among them,alcohols having 1 to 3 carbon atoms which have less carbon atoms arepreferred. They are more preferably ethanol, n-propanol and isopropanol,particularly preferably ethanol.

The aldehydes include ethanal (acetaldehyde), propanal, n-butanal andn-pentanal.

The amines include ethylamine, diethylamine, trimethylamine,diethylmethylamine and the like.

The carboxylic acids include acetic acid, propionic acid, butanoic acid,pentanoic acid and the like.

The compounds can be used in combination of two or more kinds thereof.

Among the compounds, the alcohols are particularly preferably used.

In general, the electron donor (a) has a high reactivity with theorganic metal compound catalyst component (II) described later anddevelops quickly a catalyst activity, and therefore the catalyst havinga high polymerization activity for ethylene is obtained in many cases.

The electron donor (b) having 6 to 30 carbon atoms, more preferably 6 to20 carbon atoms is used.

The specific examples of the alcohol which is the electron donor (b)include:

-   aliphatic alcohols such as hexanol, 2-methylpentanol,    2-ethylbutanol, n-heptanol, n-octanol, 2-ethylhexanol, decanol and    dodecanol;-   alicyclic alcohols such as cyclohexanol and methylcyclohexanol;-   aromatic alcohols such as benzyl alcohol and methylbenzyl alcohol;    and-   alkoxy group-containing aliphatic alcohols such as n-butyl    cellosolve. Among them, the aliphatic alcohols are used.

Examples of the aldehydes include aldehydes having 7 or more carbonatoms such as capric aldehyde and 2-ethylhexylaldehyde.

Examples of the amines include amines having 6 to 30 carbon atoms suchas heptylamine, octylamine, nonylamine, laurylamine and2-ethylhexylaminde.

Examples of the carboxylic acids include the organic carboxylic acidshaving 6 to 30 carbon atoms such as caprylic acid and 2-ethylhexanoicacid.

The electron donor (b) tends to make it possible to solubilize themagnesium compound with a small amount (mole unit).

The electron donor (b) is preferably alcohols, and alcohols having 6 to12 carbon atoms are more preferably used. The specific preferredexamples thereof are aliphatic alcohols such as hexanol, 2-ethylhexanol,decanol and dodecanol, and they are particularly preferably2-ethylhexanol.

In combination of the electron donor (a) and the electron donor (b),both of them are preferably alcohols.

The used amounts of the magnesium compound, the electron donor (a) andthe electron donor (b) in preparing the liquid magnesium compound (A)are, though varied depending on the kinds thereof and the contactconditions, 0.1 to 20 mol, preferably 0.2 to 10 mol and more preferably0.2 to 8 mol for the electron donor (a) based on 1 mol of the magnesiumcompound and 0.5 to 20 mol, preferably 1 to 10 mol and more preferably 1to 5 mol for the electron donor (b) based on the same. Also, the totalof the electron donor (a) and the electron donor (b) accounts for 1.1 to25 mol, more preferably 1.5 to 10 mol and further preferably 2 to 5 molbased on 1 mol of the magnesium compound.

The electron donor (a) is used preferably in a smaller amount than thatof the electron donor (b). To be specific, (the used amount (mol) of theelectron donor (a))/(the used amount (mol) of the electron donor (b)) ispreferably less than 1, more preferably less than 0.8, furtherpreferably less than 0.6, particularly preferably less than 0.5 andespecially preferably less than 0.4. If a proportion of the used amountsof the electron donor (a) and the electron donor (b) is out of theranges, the magnesium compound is less liable to be dissolved in acertain case. Also, the electron donor (a), the electron donor (b) andthe electron donor (B) are preferably hetero atom-containing compoundsexcluding cyclic ether compounds.

A solvent-soluble magnesium compound is advantageously used in order toobtain catalyst particles having an excellent particle property. On theother hand, the electron donor (a) is preferably used, as describedabove, in order to obtain the highly active solid titanium catalystcomponent (I) for ethylene polymerization. In the present invention,even if the electron donor (a) and the electron donor (b) are used incombination, the solid titanium catalyst component (I) for ethylenepolymerization having an excellent particle property can be obtained, tobe surprised, without damaging an effect of showing the high activity inthe ethylene polymerization.

The liquid magnesium compound (A) is preferably prepared in a liquidhydrocarbon medium. Magnesium in the liquid hydrocarbon medium is usedin a concentration of 0.1 to 20 mol/liter, preferably 0.5 to 5mol/liter. The liquid hydrocarbon media include publicly knownhydrocarbon compounds such as heptane, octane and decane as thepreferred examples.

Electron Donor (B):

Electron donors used for preparing solid titanium catalyst componentsfor polymerization of α-olefins described in Japanese Patent ApplicationLaid-Open No. 83006/1983 and Japanese Patent Application Laid-Open No.811/1981 can be listed as the preferred examples of the electron donor(B) used for preparing the solid titanium catalyst component (I) forethylene polymerization according to the present invention.

To be specific, a dicarboxylic ester compound is listed, and to be morespecific, a dicarboxylic ester compound having plural carboxylic estergroups and represented by the following Formula (1) is listed. Thedicarboxylic ester compound represented by the following Formula (1) ispreferably used from the viewpoint that it is excellent in controlling amolecular weight and a molecular weight distribution of the resultingethylene polymer. In Formula (1), C^(a) represents a carbon atom.

In Formula (1), R² and R³ each represent independently COOR¹ or R, andat least one of R² and R³ is COOR¹.

All of carbon-carbon bonds in a framework of Formula (1) are preferablysingle bonds, and any carbon-carbon bond other than a C^(a)-C^(a) bondin the framework may be substituted with a double bond.

A plurality of R¹ each is independently a monovalent hydrocarbon grouphaving 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, morepreferably 1 to 8 carbon atoms and particularly preferably 2 to 3 carbonatoms. The hydrocarbon groups include methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, neopentyl, hexyl, heptyl, octyl,2-ethylhexyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyland the like. It is preferably methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, neopentyl, hexyl, heptyl, octyl, 2-ethylhexyl anddecyl, more preferably methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, neopentyl, hexyl, heptyl, octyl and 2-ethylhexyl. Ethyl,n-propyl and isopropyl are particularly preferred.

A plurality of R each is independently an atom or a group selected froma hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, ahalogen atom, a nitrogen-containing group, an oxygen-containing group, aphosphorus-containing group, a halogen-containing group and asilicon-containing group.

Among them, a hydrocarbon group having 1 to 20 carbon atoms is preferredas R other than a hydrogen atom, and a hydrocarbon group having 1 to 10carbon atoms is more preferred. The hydrocarbon groups include, forexample, aliphatic hydrocarbon groups, alicyclic hydrocarbon groups andaromatic hydrocarbon groups such as methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, n-pentyl, cyclopentyl, n-hexyl,cyclohexyl, vinyl, phenyl and octyl, and they include preferablyaliphatic hydrocarbon groups such as methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl and n-pentyl. It is particularly preferablyethyl, n-propyl and isopropyl.

When R is such the group, it is preferred from the viewpoint that notonly a solvent-soluble component originating in a low molecular weightdescribed later can be inhibited from being produced but also it isexcellent as well in a particle property.

Further, at least two groups of R may be linked together to form a ring,and a double bond and a hetero atom may be contained in a framework ofthe ring formed by combining R with each other. When two or more C^(a)to which COOR¹ is bonded are contained in the framework of the ring, thenumber of carbon atoms forming the framework of the ring is 5 to 10.

R² and R³ which are not COOR¹ are preferably a hydrogen atom or ahydrocarbon group.

Among them, preferred are a hydrogen atom, a secondary alkyl group, forexample, isopropyl, sec-butyl, 2-pentyl and 3-pentyl or a cycloalkylgroup, for example, cyclohexyl, cyclopentyl and cyclohexylmethyl. Amongthem, at least one of R² and R³ which are not COOR¹ bonded to C^(a) ispreferably a hydrogen atom.

The examples of the dicarboxylic ester compound represented by Formula(1) include diethyl 2,3-bis(2-ethylbutyl)succinate, diethyl2,3-dibenzylsuccinate, diethyl 2,3-diisopropylsuccinate, diisobutyl2,3-diisopropylsuccinate, diethyl 2,3-bis(cyclohexylmethyl)succinate,diethyl 2,3-diisobutylsuccinate, diethyl 2,3-dineopentylsuccinate,diethyl 2,3-dicyclopentylsuccinate and diethyl 2,3-dicyclohexylsuccinatein a pure (S, R) (S, R) form or optional racemic mixture. Thedicarboxylic ester compounds are preferred from the viewpoint that theyare excellent in controlling a molecular weight and a molecular weightdistribution of the resulting ethylene polymer.

The other examples include diethyl sec-butylsuccinate, diethylthexylsuccinate, diethyl cyclopropylsuccinate, diethylnorbornylsuccinate, diethyl(10-)perhydronaphthylsuccinate, diethyltrimethylsilylsuccinate, diethyl methoxysuccinate, diethylp-methoxyphenylsuccinate, diethyl p-chlorophenylsuccinate, diethylphenylsuccinate, diethyl cyclohexylsuccinate, diethyl benzylsuccinate,diethyl(cyclohexylmethyl)succinate, diethyl t-butylsuccinate, diethylisobutylsuccinate, diethylisopropylsuccinate, diethylneopentylsuccinate,

diethyl 2,2-dimethylsuccinate, diethyl 2-ethyl-2-methylsuccinate,diethyl 2-benzyl-2-isopropylsuccinate, diethyl2-(cyclohexylmethyl)-2-isobutylsuccinate, diethyl2-cyclopentyl-2-n-propylsuccinate, diethyl 2,2-diisobutylsuccinate,diethyl 2-cyclohexyl-2-ethylsuccinate, diethyl2-isopropyl-2-methylsuccinate, diethyl 2,2-diisopropylsuccinate, diethyl2-isobutyl-2-ethylsuccinate, diethyl2-(1,1,1-trifluoro-2-propyl)-2-methylsuccinate, diethyl2-isopentyl-2-isobutylsuccinate, diethyl 2-phenyl-2-n-butylsuccinate,diisobutyl 2,2-dimethylsuccinate, diisobutyl 2-ethyl-2-methylsuccinate,diisobutyl 2-benzyl-2-isopropylsuccinate, diisobutyl2-(cyclohexylmethyl)-2-isobutylsuccinate, diisobutyl2-cyclopentyl-2-n-propylsuccinate, diethyl cyclobutane-1,2-dicarboxylateand diethyl 3-methylcyclobutane-1,2-dicarboxylate.

The suitable examples of the compound having a ring structure formed bycombining the R groups with each other in Formula (1) include a compoundrepresented by the following Formula (2). In the following Formula (2),C^(a) and C^(b) represent a carbon atom.

In Formula (2), n is an integer of 5 to 10, preferably an integer of 5to 8, more preferably an integer of 5 to 7 and most preferably 6.

R² and R³ each are independently COOR¹ or R′, and at least one of R² andR³ is COOR¹. R² is preferably COOR¹, and R³ is preferably R′.

All of carbon-carbon bonds in a cyclic framework are preferably singlebonds, and in the cyclic framework any carbon-carbon bond other than aC^(a)-C^(a) bond an a C^(a)-C^(b) bond when R³ is a hydrogen atom may besubstituted with a double bond.

A plurality of R¹ is a hydrocarbon group having 1 to 20 carbon atoms asis the case with R¹ in Formula (1), preferably a hydrocarbon grouphaving 1 to 8 carbon atoms and more preferably a hydrocarbon grouphaving 2 to 3 carbon atoms. The suitable examples of R¹ are methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl, neopentyl and2-ethylhexyl, more preferably ethyl, n-propyl and isopropyl.

In Formula (2), A is:

or a hetero atom excluding an oxygen atom.

-   A is preferably:

and a ring formed by C^(a), C^(b) and A is preferably a cyclic carbonstructure, and is particularly preferably a saturated alicyclicstructure wherein the cyclic structure is constituted only by carbons.

A plurality of R′ each is independently an atom or a group selected froma hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, ahalogen atom, a nitrogen-containing group, an oxygen-containing group, aphosphorus-containing group, a halogen-containing group and asilicon-containing group.

Among them, a hydrocarbon group having 1 to 20 carbon atoms is preferredas R′ other than a hydrogen atom, and a hydrocarbon group having 1 to 10carbon atoms is more preferred. The hydrocarbon groups include, forexample, aliphatic hydrocarbon groups, alicyclic hydrocarbon groups andaromatic hydrocarbon groups such as methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, n-pentyl, cyclopentyl, n-hexyl,cyclohexyl, vinyl, phenyl and octyl, preferably aliphatic hydrocarbongroups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,sec-butyl and n-pentyl, and it is particularly preferably ethyl,n-propyl and isopropyl.

When R′ is such the group, it is preferred from the viewpoint that notonly a solvent-soluble component originating in a low molecular weightdescribed later can be inhibited from being produced but also it isexcellent as well in a particle property.

Further, R′ may be linked each other to form a ring, and a double bondand a hetero atom excluding an oxygen atom may be contained in aframework of the ring formed by combining R′ with each other. When twoor more C^(a) to which COOR¹ is bonded are contained in the framework ofthe ring, the number of carbon atoms forming the framework of the ringis 5 to 10.

The frameworks of the rings include a norbornane framework, atetracyclododecane framework and the like.

A plurality of R′ may be a carboxylic ester group, an alkoxy group, asiloxy group, a carbonyl structure-containing group such as an aldehydegroup and an acetyl group.

R′ is preferably a hydrogen atom or a hydrocarbon group.

The dicarboxylic ester compounds represented by the Formula (2) includediethyl cyclohexane-1,2-dicarboxylate, di-n-propylcyclohexane-1,2-dicarboxylate, diisopropylcyclohexane-1,2-dicarboxylate, diethyl cyclohexane-1,3-dicarboxylate,di-n-propyl cyclohexane-1,3-dicarboxylate, diisopropylcyclohexane-1,3-dicarboxylate, diethyl3-methylcyclohexane-1,2-dicarboxylate, di-n-propyl3-methylcyclohexane-1,2-dicarboxylate, diisopropyl3-methylcyclohexane-1,2-dicarboxylate, diethyl4-methylcyclohexane-1,3-dicarboxylate, di-n-propyl4-methylcyclohexane-1,3-dicarboxylate, diethyl4-methylcyclohexane-1,2-dicarboxylate, di-n-propyl4-methylcyclohexane-1,2-dicarboxylate, diisopropyl4-methylcyclohexane-1,2-dicarboxylate, diethyl5-methylcyclohexane-1,3-dicarboxylate, di-n-propyl5-methylcyclohexane-1,3-dicarboxylate, diisopropyl5-methylcyclohexane-1,3-dicarboxylate, diethyl3,4-dimethylcyclohexane-1,2-dicarboxylate, di-n-propyl3,4-dimethylcyclohexane-1,2-dicarboxylate, diisopropyl3,4-dimethylcyclohexane-1,2-dicarboxylate, diethyl3,6-dimethylcyclohexane-1,2-dicarboxylate, di-n-propyl3,6-dimethylcyclohexane-1,2-dicarboxylate, diisopropyl3,6-dimethylcyclohexane-1,2-dicarboxylate, diethyl3-hexylcyclohexane-1,2-dicarboxylate, di-n-propyl3-hexylcyclohexane-1,2-dicarboxylate, di-n-propyl3,6-dihexylcyclohexane-1,2-dicarboxylate, diethyl3-hexyl-6-pentylcyclohexane-1,2-dicarboxylate, diethylcyclopentane-1,2-dicarboxylate, di-n-propylcyclopentane-1,2-dicarboxylate, diisopropylcyclopentane-1,2-dicarboxylate, diethyl cyclopentane-1,3-dicarboxylate,di-n-propyl cyclopentane-1,3-dicarboxylate, diethyl3-methylcyclopentane-1,2-dicarboxylate, di-n-propyl3-methylcyclopentane-1,2-dicarboxylate, diisopropyl3-methylcyclopentane-1,2-dicarboxylate, diethyl4-methylcyclopentane-1,3-dicarboxylate, di-n-propyl4-methylcyclopentane-1,3-dicarboxylate, diisopropyl4-methylcyclopentane-1,3-dicarboxylate, diethyl4-methylcyclopentane-1,2-dicarboxylate, di-n-propyl4-methylcyclopentane-1,2-dicarboxylate, diisopropyl4-methylcyclopentane-1,2-dicarboxylate, diethyl5-methylcyclopentane-1,3-dicarboxylate, di-n-propyl5-methylcyclopentane-1,3-dicarboxylate, diethyl3,4-dimethylcyclopentane-1,2-dicarboxylate, di-n-propyl3,4-dimethylcyclopentane-1,2-dicarboxylate, diisopropyl3,4-dimethylcyclopentane-1,2-dicarboxylate, diethyl3,5-dimethylcyclopentane-1,2-dicarboxylate, di-n-propyl3,5-dimethylcyclopentane-1,2-dicarboxylate, diisopropyl3,5-dimethylcyclopentane-1,2-dicarboxylate, diethyl3-hexylcyclopentane-1,2-dicarboxylate, diethyl3,5-dihexylcyclopentane-1,2-dicarboxylate, diethylcycloheptane-1,2-dicarboxylate, di-n-propylcycloheptane-1,2-dicarboxylate, diisopropylcycloheptane-1,2-dicarboxylate, diethyl cycloheptane-1,3-dicarboxylate,di-n-propyl cycloheptane-1,3-dicarboxylate, diethyl3-methylcycloheptane-1,2-dicarboxylate, di-n-propyl3-methylcycloheptane-1,2-dicarboxylate, diisopropyl3-methylcycloheptane-1,2-dicarboxylate, diethyl4-methylcycloheptane-1,3-dicarboxylate, diethyl4-methylcycloheptane-1,2-dicarboxylate, di-n-propyl4-methylcycloheptane-1,2-dicarboxylate, diisopropyl4-methylcycloheptane-1,2-dicarboxylate, diethyl5-methylcycloheptane-1,3-dicarboxylate, diethyl3,4-dimethylcycloheptane-1,2-dicarboxylate, di-n-propyl3,4-dimethylcycloheptane-1,2-dicarboxylate, diisopropyl3,4-dimethylcycloheptane-1,2-dicarboxylate, diethyl3,7-dimethylcycloheptane-1,2-dicarboxylate, di-n-propyl3,7-dimethylcycloheptane-1,2-dicarboxylate, diisopropyl3,7-dimethylcycloheptane-1,2-dicarboxylate, diethyl3-hexylcycloheptane-1,2-dicarboxylate, diethyl3,7-dihexylcycloheptane-1,2-dicarboxylate, diethylcyclooctane-1,2-dicarboxylate, diethyl3-methylcyclooctane-1,2-dicarboxylate, diethylcyclodecane-1,2-dicarboxylate, diethyl3-methylcyclodecane-1,2-dicarboxylate, diethylcyclooxypentane-3,4-dicarboxylate, diethyl3,6-dicyclohexylcyclohexane-1,2-dicarboxylate and the like.

Isomers such as cis and trans compounds are present in the compoundshaving a diester structure, and the compounds having either structurehave effects which meet the objects of the present invention in manycases.

Among the compounds, the cyclohexanedicarboxylic esters in which n is 6in Formula (2) are particularly preferred. The reason therefor residesnot only in the catalyst performances thereof but also in that thecompounds can be produced at relatively lower costs by making use of aDiels Alder reaction.

Further, when the cyclohexanedicarboxylic esters are used, the catalystsare excellent in a hydrogen response and maintain a high activity, andpolymers which are excellent in a particle property can be obtained.

Also, acid halides, acid amides, nitriles, acid anhydrides, organic acidesters and polyethers each shown below can also be used as the electrondonor (B).

To be specific, they include acid halides having 2 to 15 carbon atomssuch as acetyl chloride, benzoyl chloride, toluyl chloride and anisylchloride;

-   acid amides such as N,N-dimethylacetamide, N,N-diethylbenzamide and    N,N-dimethyltoluamide;-   nitriles such as acetonitrile, benzonitrile and trinitrile; acid    anhydrides such as acetic anhydride, phthalic anhydride and benzoic    anhydride;-   organic acid esters having 2 to 18 carbon atoms such as methyl    formate, methyl acetate, ethyl acetate, vinyl acetate, propyl    acetate, octyl acetate, cyclohexyl acetate, ethyl propionate, methyl    butyrate, ethyl valerate, methyl chloroacetate, ethyl    dichloroacetate, methyl methacrylate, ethyl crotonate, methyl    benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, octyl    benzoate, cyclohexyl benzoate, phenyl benzoate, benzyl benzoate,    methyl toluate, ethyl toluate, amyl toluate, ethyl ethylbenzoate,    methyl anisate, ethyl anisate, ethyl ethoxybenzoate,    .gamma.-butyllactone, .delta.-valerolactone, coumarin, phthalide and    ethyl carbonate. Among the organic acid esters, benzoic acid esters    such as methyl benzoate, ethyl benzoate, propyl benzoate, butyl    benzoate, octyl benzoate, cyclohexyl benzoate, phenyl benzoate,    benzyl benzoate, ethyl ethylbenzoate and ethyl ethoxybenzoate are    preferably used in terms of prices, a safety and an availability.

Further, publicly known polyhydric carboxylic esters can be listed. Thepolyhydric carboxylic esters include, to be specific, aliphaticpolycarboxylic esters such as diethyl succinate, dibutyl succinate,diethyl methylmalonate, diethyl ethylmalonate, diethylisopropylmalonate, diethyl butylmalonate, diethyl phenylmalonate,diethyl diethylmalonate, diethyl dibutylmalonate, monooctyl maleate,dioctyl maleate, dibutyl maleate, dibutyl butylmaleate, diethylbutylmaleate, di-2-ethylhexyl fumarate, diethyl itaconate and dioctylcitraconate, aromatic polycarboxylic esters such as phthalates,naphthalenedicarboxylates, triethyl trimellitate and dibutyltrimellitate; heterocyclic polycarboxylic esters such as3,4-furandicarboxylates. However, among the compounds, themultifunctional aromatic compounds are preferably prevented from beingused or used only in a minimum necessary amount in a certain casebecause of the reasons of safety and health and the like.

Also, other examples of the polyhydric carboxylic esters include estersof long chain dicarboxylic acids, such as diethyl adipate, diisobutyladipate, diisopropyl sebacate, di-n-butyl sebacate, di-n-octyl sebacateand di-2-ethylhexyl sebacate.

The specific examples of the electron donor (B) include the polyethers,that is, compounds (hereinafter referred to as “polyethers”) having twoor more ether bonds which are present via plural atoms. Compounds inwhich carbon, silicon, oxygen, nitrogen, sulfur, phosphorus, boron ortwo or more atoms selected from them are present between ether bonds canbe listed as the polyethers. Among them, preferred are the compounds inwhich a relatively bulky substituent is bonded to an atom presentbetween ether bonds and in which plural carbon atoms are included inatoms present between two or more ether bonds. For example, a diethercompound represented by the following Formula (3) is preferred:

In Formula (3), m is an integer of 1 to 10, more preferably 3 to 10 andparticularly preferably 3 to 5. R¹¹, R¹² and R³¹ to R³⁶ each areindependently a hydrogen atom or a substituent having at least oneelement selected from carbon, hydrogen, oxygen, fluorine, chlorine,bromine, iodine, nitrogen, sulfur, phosphorus, boron and silicon.

R¹¹ and R¹² are preferably a hydrocarbon group having 1 to 10 carbonatoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms,and R³¹ to R³⁶ are preferably a hydrogen atom or a hydrocarbon grouphaving 1 to 6 carbon atoms.

R¹¹ and R¹² are, to be specific, methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, isopentyl, neopentyl, hexyl, heptyl, octyl,2-ethylheptyl, decyl, cyclopentyl and cyclohexyl, and they arepreferably ethyl, n-propyl, isopropyl, n-butyl and isobutyl.

R³¹ to R³⁶ include, to be specific, a hydrogen atom, methyl, ethyl,n-propyl, isopropyl, n-butyl and isobutyl, and they are preferably ahydrogen atom and methyl.

Any ones of R¹¹, R¹² and R³¹ to R³⁶, preferably R¹¹ and R¹² may belinked each other to form a ring other than a benzene ring, and atomsother than carbon may be contained in a main chain.

The specific examples of the compound having two or more ether bondsinclude

-   2,2-dicyclohexyl-1,3-dimethoxypropane,-   2,2-diethyl-1,3-dimethoxypropane,-   2,2-dipropyl-1,3-dimethoxypropane,-   2,2-dibutyl-1,3-dimethoxypropane,-   2-methyl-2-propyl-1,3-dimethoxypropane,-   2-methyl-2-ethyl-1,3-dimethoxypropane,-   2-methyl-2-isopropyl-1,3-dimethoxypropane,-   2-methyl-2-cyclohexyl-1,3-dimethoxypropane,-   2,2-bis(2-cyclohexylethyl)-1,3-dimethoxypropane,-   2-methyl-2-isobutyl-1,3-dimethoxypropane,-   2-methyl-2-(2-ethylhexyl)-1,3-dimethoxypropane,-   2,2-diisobutyl-1,3-dimethoxypropane,-   2,2-bis(cyclohexylmethyl)-1,3-dimethoxypropane,-   2,2-diisobutyl-1,3-diethoxypropane,-   2,2-diisobutyl-1,3-dibuthoxypropane,-   2-isobutyl-2-isopropyl-1,3-dimethoxypropane,-   2,2-di-s-butyl-1,3-dimethoxypropane,-   2,2-di-t-butyl-1,3-dimethoxypropane,-   2,2-dineopentyl-1,3-dimethoxypropane,-   2-isopropyl-2-isopentyl-1,3-dimethoxypropane,-   2-cyclohexyl-2-cyclohexylmethyl-1,3-dimethoxypropane,-   2,3-dicyclohexyl-1,4-diethoxybutane,-   2,3-diisopropyl-1,4-diethoxybutane,-   2,4-diisopropyl-1,5-dimethoxypentane,-   2,4-diisobutyl-1,5-dimethoxypentane,-   2,4-diisoamyl-1,5-dimethoxypentane,-   3-methoxymethyltetrahydrofuran,-   3-methoxymethyldioxane,-   1,2-diisobutoxypropane,-   1,2-diisobutoxyethane,-   1,3-diisoamyloxyethane,-   1,3-diisoamyloxypropane,-   1,3-diisoneopentyloxyethane,-   1,3-dineopentyloxypropane,-   2,2-tetramethylene-1,3-dimethoxypropane,-   2,2-pentamethylene-1,3-dimethoxypropane,-   2,2-hexamethylene-1,3-dimethoxypropane,-   1,2-bis(methoxymethyl)cyclohexane,-   2-cyclohexyl-2-ethoxymethyl-1,3-diethoxypropane,-   2-cyclohexyl-2-methoxymethyl-1,3-dimethoxypropane,-   2,2-diisobutyl-1,3-dimethoxycyclohexane,-   2-isopropyl-2-isoamyl-1,3-dimethoxycyclohexane,-   2-cyclohexyl-2-methoxymethyl-1,3-dimethoxycyclohexane,-   2-isopropyl-2-methoxymethyl-1,3-dimethoxycyclohexane,-   2-isobutyl-2-methoxymethyl-1,3-dimethoxycyclohexane,-   2-cyclohexyl-2-ethoxymethyl-1,3-diethoxycyclohexane,-   2-cyclohexyl-2-ethoxymethyl-1,3-dimethoxycyclohexane,-   2-isopropyl-2-ethoxymethyl-1,3-diethoxycyclohexane,-   2-isopropyl-2-ethoxymethyl-1,3-dimethoxycyclohexane,-   2-isobutyl-2-ethoxymethyl-1,3-diethoxycyclohexane and-   2-isobutyl-2-ethoxymethyl-1,3-dimethoxycyclohexane.

Among them, 1,3-diethers are preferred, and particularly preferred are2-isopropyl-2-isobutyl-1,3-dimethoxypropane,2,2-diisobutyl-1,3-dimethoxypropane,2-isopropyl-2-isopentyl-1,3-dimethoxypropane,2,2-dicyclohexyl-1,3-dimethoxypropane and2,2-bis(cyclohexylmethyl)-1,3-dimethoxypropane.

Further, an alkoxysilane compound represented by a formulaR_(n)Si(OR′)_(4-n) described later and tetraalkoxysilane compounds suchas tetraethoxysilane and tetrabutoxysilane can be shown as the examplesof the electron donor (B).

The compounds listed as the electron donor (B) may be used alone or twoor more kinds of the compounds may be used in combination.

Among them, the dicarboxylic esters having the cyclic structurerepresented by Formula (2) or mixtures of the organic acid esters withthe diether compound represented by Formula (3) are particularlypreferred.

Among the preferred electron donors (B), the dicarboxylic esters or theorganic acid esters may be formed in a step for preparing the solidtitanium catalyst component (I) for ethylene polymerization. They can beformed as well, for example, in a step for bringing them into contactwith the magnesium compound (A). To be more specific, the electron donor(B) can be incorporated into the solid titanium catalyst component byproviding a step in which carboxylic anhydride corresponding to thecompound and alcohol corresponding to the carboxylic halide aresubstantially brought into contact therewith in bringing them intocontact with the magnesium compound (A).

According to investigations of the present inventors, it can be foundthat if the electron donor (B) is used, the solvent-soluble componenttends to be less by-produced, as shown in FIG. 1, when the polymershaving a similar intrinsic viscosity [η], that is, a similar molecularweight are compared. Also, if the electron donor (B) is used, the solidtitanium catalyst component having a good particle property tends to bereadily obtained.

Liquid Titanium Compound (C):

The liquid titanium compound (C) used for preparing the solid titaniumcatalyst component (I) for ethylene polymerization according to thepresent invention may be titanium compounds described in JP 1983-83006and JP 1981-811. A tetravalent titanium compound represented by thefollowing Formula (4) can be listed as the specific example of theliquid titanium compound (C):Ti(OR)_(g)X_(4-g)  (4)wherein R is an aliphatic hydrocarbon group having 1 to 5 carbon atoms;X is a halogen atom; and g shows 0≦g≦4.

The specific examples of the tetravalent titanium compounds representedby Formula (4) include titanium tetrahalides such as TiCl₄ and TiBr₄;alkoxytitanium trihalides such as Ti(OCH₃)Cl₃, Ti(OC₂H₅)Cl₃,Ti(O-n-C₄H₉)Cl₃, Ti(OC₂H₅)Br₃ and Ti(O-iso-C₄H₉)Br₃; alkoxytitaniumdihalides such as Ti(OCH₃)₂Cl₂ and Ti(OC₂H₅)₂Cl₂; alkoxytitaniummonohalides such as Ti(OCH₃)₃Cl, Ti(O-n-C₄H₉)₃Cl and Ti(OC₂H₅)₃Br; andtetraalkoxytitaniums such as Ti(OCH₃)₄, Ti(OC₂H₅)₄, Ti(OC₄H₉)₄ andTi(O-2-ethylhexyl)₄.

Among them, the titanium tetrahalides are preferred, and titaniumtetrachloride is particularly preferred. The titanium compounds may beused alone or in combination of two or more kinds thereof.

In the present invention, it is preferable that at least one of theliquid magnesium compound (A) and the liquid titanium compound (C)contains halogen.

When both of the liquid magnesium compound (A) and the titanium compound(C) do not contain halogen, they can be brought into contact with apublicly known halogen-containing compound such as halogen-containingsilicon compounds in an optional step. Representative examples of thehalogen-containing compounds include silicon tetrachloride.

Preparation of Solid Titanium Catalyst Component (I) for EthylenePolymerization:

The solid titanium catalyst component (I) for ethylene polymerizationaccording to the present invention is obtained by bringing the liquidmagnesium compound (A) into contact with the liquid titanium compound(C) under the presence of the electron donor (B). In this case, theliquid magnesium compound (A) may be in a state in which it is dissolvedin a publicly known liquid hydrocarbon medium, for example, heptane,octane and decane.

If the liquid magnesium compound (A) and the liquid titanium compound(C) are brought into contact with the electron donor (B) aftercompletely finishing contact of the liquid magnesium compound (A) withthe liquid titanium compound (C), amorphous particles and fine particlestend to be formed. In this case, the refining step carried out byfiltration and decantation is deteriorated, and the polymer obtained byusing the solid titanium catalyst component is inferior in particleproperties. Thus, problems such as a reduction in the productivity andthe handling property are brought about in a certain case.

As long as these requisites are satisfied, a publicly known methodcomprising bringing the liquid magnesium compound (A), the electrondonor (B) and the liquid titanium compound (C) into contact with oneanother to obtain a solid titanium catalyst component can be usedwithout any limitations. For example, the following methods (P-1) to(P-5) can be listed.

-   (P-1): a method comprising bringing a mixture of the liquid    magnesium compound (A) and the electron donor (B) into contact with    the liquid titanium compound (C) to deposit a solid titanium    complex.-   (P-2): a method comprising reacting a mixture of the liquid    magnesium compound (A) and the electron donor (B) with the liquid    titanium compound (C), and further bringing it into contact with the    liquid titanium compound (C) in several batches to deposit a solid    titanium complex.-   (P-3): a method comprising bringing the liquid magnesium compound    (A), the electron donor (B) and the liquid titanium compound (C)    into contact at the same time to deposit a solid titanium complex.    In this case, the electron donor (B) may be, if necessary, brought    into contact in an optional step.-   (P-4): a method comprising bringing a mixture of the liquid    magnesium compound (A) and the electron donor (B) into contact with    the liquid titanium compound (C), and further bringing it into    contact with the electron donor (B) to deposit a solid titanium    complex. In this case, the liquid titanium compound (C) may be    brought into contact in several batches.-   (P-5): a method comprising bringing the liquid magnesium    compound (A) into contact with a mixture of the electron donor (B)    and the liquid titanium compound (C) to deposit a solid titanium    complex. In this case, the electron donor (B) may be, if necessary,    brought into contact in an optional step, and the liquid titanium    compound (C) may be brought into contact in several batches.

As described above, the electron donor (B) may be brought into contactagain after finishing bringing the liquid magnesium compound (A) intocontact with the liquid titanium compound (C).

According to the method in which the liquid obtained by mixing inadvance the liquid magnesium compound (A) with the electron donor (B) isused among the methods, the resulting solid titanium catalyst componentis provided with good particle properties (amorphous particles and fineparticles are less liable to be produced), and the refining step carriedout by filtration and decantation favorably proceeds, so that it ispreferred in terms of the productivity and the handling property.

In the present invention, the electron donor (B) is used in an amountfalling in the range of preferably 0.005 to 5 mol, more preferably 0.01to 2 mol and particularly preferably 0.03 to 1 mol based on 1 mol of theliquid magnesium compound (A). However, the preferred ranges are variedin a certain case according to the liquid titanium compound (C) usage.

In the present invention, the liquid titanium compound (C) is used in anamount falling in the range of preferably 0.1 to 100 mol, morepreferably 0.5 to 80 mol, further preferably 1 to 70 mol andparticularly preferably 5 to 70 mol based on 1 mol of the liquidmagnesium compound (A).

Halogen/titanium (atomic ratio) contained in the solid titanium catalystcomponent (I) for ethylene polymerization according to the presentinvention is 2 to 100, preferably 4 to 90, and magnesium/titanium(atomic ratio) is 1 to 100, preferably 1 to 50.

A molar ratio between the electron donor (B), the electron donor (a) orthe electron donor (b), and a titanium atom each contained in the solidtitanium catalyst component (I) for ethylene polymerization according tothe present invention is 0 to 100, preferably 0.01 to 10 and morepreferably 0.2 to 10.

<Ethylene Polymerization Catalyst>

The ethylene polymerization catalyst according to the present inventioncomprises the solid titanium catalyst component (I) for ethylenepolymerization obtained in the manner described above and the organicmetal compound catalyst component (II). The above organic metal compoundcatalyst component (II) is preferably an organic metal compoundcontaining metal selected from a 1st group, a 2nd group and a 13th groupin the periodic table, and capable of being used are, for example,organic aluminum compounds, alkyl complexes of 1st group metals withaluminum and organic metal compounds of 2nd group metal such as Grignardreagents and organic magnesium compounds. Among them, the organicaluminum compounds are preferred.

Organic Metal Compound Catalyst Component (II):

Preferred examples of the organic metal compound catalyst component (II)include organic metal compound catalyst components described in publiclyknown documents such as EP585869A1. They are particularly preferablyorganic aluminum compounds such as triethylaluminum, tributylaluminum,triisobutylaluminum, trioctylaluminum and diethylaluminum hydride.

Electron Donor (III):

The ethylene polymerization catalyst of the present invention cancomprise, if necessary, an electron donor (III) in addition to theorganic metal compound catalyst component (II). The electron donor (III)is preferably an organic silicon compound. For example, a compoundrepresented by the following Formula (5) can be listed as the organicsilicon compound:R_(n)Si(OR′)_(4-n)  (5)wherein R and R′ are aliphatic, alicyclic or aromatic hydrocarbon groupshaving 1 to 20 carbon atoms; and n represents 0<n<4.

Used as the organic silicon compound represented by Formula (5) are, tobe specific, diisopropyldimethoxysilane, t-butylmethyldimethoxysilane,t-butylmethyldiethoxysilane, t-amylmethyldiethoxysilane,dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane,cyclohexylmethyldiethoxysilane, vinyltrimethoxysilane,vinyltriethoxysilane, t-butyltriethoxysilane, phenyltriethoxysilane,cyclohexyltrimethoxysilane, cyclopentyltrimethoxysilane,2-methylcyclopentyltrimethoxysilane, cyclopentyltriethoxysilane,dicyclopentyldimethoxysilane, dicyclopentyldiethoxysilane,tricyclopentylmethoxysilane, dicyclopentylmethylmethoxysilane,dicyclopentylethylmethoxysilane and cyclopentyldimethylethoxysilane.

Among them, vinyltriethoxysilane, diphenyldimethoxysilane,dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane,dicyclopentyldimethoxysilane and the like are preferably used. Theorganic silicon compounds can be used in a mixture of two or more kindsthereof.

The compounds shown as the examples of the electron donor (B), theelectron donor (a) and the electron donor (b) each used for the solidtitanium catalyst component (I) for ethylene polymerization can belisted as the other electron donors (III). Among them, the polyetherscan be listed as the preferred examples thereof.

In the present invention, the ethylene polymerization catalyst cancomprise, if necessary, other components useful for olefinpolymerization, such as antistatic agents, particle flocculants andstorage stabilizers in addition to the respective components.

The ethylene polymerization catalyst of the present invention can beused to polymerize α-olefins such as propylene.

<Polymerization Method for Ethylene>

The ethylene polymerization method of the present invention ischaracterized by polymerizing ethylene alone or olefins containingethylene with the ethylene polymerization catalyst to obtain an ethylenepolymer. That is, ethylene is homopolymerized or copolymerized withother olefins under the presence of the ethylene polymerizationcatalyst.

In the ethylene polymerization method of the present invention, olefinis prepolymerized under the presence of the ethylene polymerizationcatalyst of the present invention to obtain a prepolymerizationcatalyst, and ethylene can be polymerized under the presence of theprepolymerization catalyst. The prepolymerization is carried out byprepolymer zing the olefin in an amount of 0.1 to 1000 g, preferably 0.3to 500 g and particularly preferably 1 to 200 g per 1 g of the ethylenepolymerization catalyst.

In the prepolymerization, the catalyst having a higher concentrationthan that of the catalyst used in the system in the main polymerizationcan be used. A concentration of the solid titanium catalyst component(I) for ethylene polymerization in the prepolymerization falls in therange of usually about 0.001 to 200 mmol, preferably about 0.01 to 50mmol and particularly preferably 0.1 to 20 mmol per 1 liter of theliquid medium in terms of a titanium atom.

The amount of the organic metal compound catalyst component (II) in theprepolymerization is such that 0.1 to 1000 g, preferably 0.3 to 500 g ofthe polymer per 1 g of the solid titanium catalyst component (I) forethylene polymerization is produced, and it is preferably an amount ofusually about 0.1 to 300 mol, preferably about 0.5 to 100 mol andparticularly preferably 1 to 50 mol per 1 mol of a titanium atomcontained in the solid titanium catalyst component (I) for ethylenepolymerization.

In the prepolymerization, the electron donor (III) and the like can beused if necessary. In this case, these components are used in an amountof 0.1 to 50 mol, preferably 0.5 to 30 mol and more preferably about 1to 10 mol per 1 mol of a titanium atom contained in the solid titaniumcatalyst component (I) for ethylene polymerization.

The prepolymerization can be carried out on mild conditions by addingolefin and the catalyst components to an inert hydrocarbon medium.

In the above case, examples of the inert hydrocarbon medium used includealiphatic hydrocarbons such as propane, butane, heptane, octane, decane,dodecane and kerosene;

-   alicyclic hydrocarbons such as cycloheptane and methylcycloheptane;-   aromatic hydrocarbons such as benzene, toluene and xylene;-   halogenated hydrocarbon such as ethylene chloride and chlorobenzene,    or mixtures thereof.

Among the inert hydrocarbon media, the aliphatic hydrocarbons areparticularly preferably used. When the inert hydrocarbon medium is used,the prepolymerization is preferably carried out by a batch system.

On the other hand, the prepolymerization can be carried out by usingolefin itself as a solvent, or prepolymerization can be carried outsubstantially in the absence of the solvent. In this case, theprepolymerization is preferably carried out in a continuous manner.

Publicly known olefins such as ethylene, propylene, 1-butene, 1-pentene,1-hexene and 4-methyl-1-pentene can be used as the olefin used in theprepolymerization. Among them, ethylene and propylene are preferred.

Temperature in the prepolymerization falls in the range of usually about−20 to +100° C., preferably about −20 to +80° C. and more preferablyabout 0 to +40° C.

Next, the main polymerization shall be explained.

In the main polymerization, ethylene can be used alone or other olefinscan be used in addition to ethylene. Examples of them include α-olefinshaving 3 to 20 carbon atoms, for example, propylene, 1-butene,1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene,1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene. Propylene,1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene and the likeare preferably used. In addition to them, aromatic vinyl compounds suchas styrene and allylbenzene and alicyclic vinyl compounds such asvinylcycloheptane can be used. Also, the compounds can be used incombination of two or more kinds thereof. Further, cyclopentene,cycloheptene, compounds having multi-unsaturated bonds such asconjugated dienes and non-conjugated dienes in dienes such asnorbornene,tetracylododecene, isoprene and butadiene can be used as polymerizationmaterials together with ethylene and the α-olefins.

In the present invention, the prepolymerization and the mainpolymerization can be carried out by either of a liquid phasepolymerization method such as solution polymerization and slurrypolymerization and a gas phase polymerization method. In particular, themain polymerization is carried out preferably by slurry polymerization.

When a reaction mode of slurry polymerization is employed in the mainpolymerization, the inert hydrocarbon used in the prepolymerization ispreferably used as a reaction solvent.

In the main polymerization in the ethylene polymerization method of thepresent invention, the solid titanium catalyst component (I) forethylene polymerization is used in an amount of usually about 0.0001 to0.5 mmol, preferably about 0.005 to 0.1 mmol in terms of a titanium atomper 1 liter of the polymerization volume. Also, the organic metalcompound catalyst component (II) is used in an amount of usually about 1to 2000 mol, preferably about 5 to 500 mol in terms of a metal atom per1 mol of a titanium atom contained in the prepolymerization catalystcomponent in the polymerization system. When the electron donor (III) isused, it is used in an amount of 0.001 to 50 mol, preferably 0.01 to 30mol and particularly preferably 0.05 to 20 mol based on 1 mol of a metalatom of the organic metal compound catalyst component (II).

Use of hydrogen in the main polymerization makes it possible to controla molecular weight of the resulting ethylene polymer, and the ethylenepolymer having a large melt flow rate (hereinafter referred to as “MFR”)is obtained. If the ethylene polymerization catalyst of the presentinvention is used, the polymer having higher MFR tends to be readilyobtained in a smaller hydrogen amount than in conventional ethylenepolymerization catalysts.

The reason why the polymer having higher MFR is liable to be obtained ina smaller hydrogen amount is unknown, but it is considered that chaintransfer reaction by hydrogen is expedited by the electron donor (B). Inparticular, a catalyst comprising the solid titanium catalyst componentin which the electron donor represented by Formula (3) is containedtends to show notably the direction.

In the main polymerization in the present invention, the polymerizationtemperature is set to usually about 20 to 250° C., preferably about 50to 200° C., and the pressure is set to usually an atmospheric pressureto 10 MPa, preferably about 0.2 to 5 MPa. The temperature in a case ofslurry polymerization is about 20 to 100° C., preferably about 50 to 90°C., and the pressure is usually an atmospheric pressure to 1.5 MPa,preferably about 0.2 to 1 MPa. In the polymerization method of thepresent invention, the polymerization can be carried out by any methodof a batch system, a semi-continuous system and a continuous system.Further, the polymerization can be carried out on changed reactionconditions in two or more stages.

The ethylene polymer obtained by the ethylene polymerization method ofthe present invention is excellent in particle properties and has a highbulk density, and therefore it can be produced at a high productivity.Further, a low molecular weight polymer which is dissolved in an inerthydrocarbon used for slurry polymerization tends to be less by-produced.A by-production amount of the solvent-soluble component is variedaccording to MFR of the ethylene polymer produced (the higher the MFRis, the higher the amount of the solvent-soluble component tends to be),and the solvent-soluble component formed in producing the polymer havingMFR of 300 to 400 g/10 minutes accounts preferably for 8% or less.

It is known that the component having such higher MFR as described aboveis preferably contained in order to allow a moldability of the ethylenepolymer to be compatible with a strength thereof. The ethylenepolymerization method of the present invention makes it possible toreduce a loss in producing the ethylene polymer.

Examples

Next, the present invention shall be specifically explained withreference to examples, but the present invention shall not be restrictedto these examples.

In the following examples, a composition, a particle size and a bulkdensity of the solid titanium catalyst component for ethylenepolymerization were measured in the following manners.

(1) Contents of Magnesium and Titanium:

Measured by ICP analysis (ICPF 1000TR, manufactured by ShimadzuCorporation).

(2) Chlorine Content:

Measured by a silver nitrate titration method.

(3) Content of Alcohol Residue:

The catalyst which was sufficiently dried was added to an acetonesolution to which 10% by weight of water was added to obtain alcohol byhydrolysis, and the amount of the alcohol residue was quantitativelydetermined by gas chromatography.

(4) Fine Powder Content (Particle Size Distribution):

A content of fine powders having a particle diameter of less than 75 μmwas measured by means of a shaker (Ro-Tap, manufactured by IidaSeisakusho Co., Ltd.) and a sieve (Bunsei Furui, inner diameter: 200 mm,aperture: 75 μm).

(5) Bulk Density (BD):

Measured according to JIS K-6721 standard.

(6) Melt Flow Rate (MFR):

Measured on a condition of 190° C. according to ASTM D1238E.

(7) Solvent-Soluble Component Ratio (SP):

Calculated according to the following equation.SP(%)=100×(α)/((α)+(β))

-   -   (α): amount of powder-like polymer    -   (β) amount of ethylene polymer dissolved in a n-heptane solvent

An amount of (β) is measured as a weight of a solid obtained by removingthe solvent by distillation from the filtrate separated by filteringafter the polymerization.

(8) Intrinsic Viscosity [η]:

The ethylene polymer particles were dissolved in decalin to measure aintrinsic viscosity [η] in decalin of 135° C.

Example 1 Preparation of Solid Titanium Catalyst Component for EthylenePolymerization

4.76 g (50 mmol) of magnesium chloride anhydrous, 28.1 ml of decane and16.3 g (125 mmol) of 2-ethylhexyl alcohol (EHA) were reacted by heatingat 130° C. for 3 hours to prepare a homogeneous solution, and then 0.94g (20 mmol) of ethyl alcohol (EtOH) was added and reacted by heating at50° C. for 1 hour. 0.96 g (3.75 mmol) of diisopropylcis-cyclohexane-1,2-dicarboxylate was added to the solution and mixed bystirring at 50° C. for further 1 hour, and then the solution wasgradually cooled down to room temperature.

A whole amount of the homogeneous solution thus obtained was dropwiseadded to 200 ml (1.8 mol) of titanium tetrachloride of 0° C. in 1 hourunder stirring. The temperature was maintained at 0° C. during dropwiseadding. After finishing addition, the mixed solution was maintained at atemperature of 0° C. for 1 hour, and then the temperature was elevatedup to 110° C. in 1 hour and 45 minutes. Thereafter, the solution wasmaintained at the temperature for 30 minutes under stirring and thenfiltrated at the same temperature to separate a solid part. This solidpart was sufficiently washed with decane of 110° C. and then with hexaneof room temperature until the free titanium compound was not detected toobtain a solid titanium catalyst component (I-1) for ethylenepolymerization. The solid titanium catalyst component thus obtained wasstored in the form of a decane suspension, and a part thereof was driedfor analysis. The composition thereof was such that 7.0% by weight oftitanium, 14% by weight of magnesium, 59% by weight of chlorine, 0.9% byweight of an ethyl alcohol residue and 6.9% by weight of a 2-ethylhexylalcohol residue.

Polymerization

An autoclave having an inner content of 1 liter was charged with 500 mlof refined n-heptane under ethylene atmosphere, and added thereto were0.25 mmol of triethylaluminum and a decane suspension of the solidtitanium catalyst component (I-1) for ethylene polymerization obtainedabove in an amount corresponding to 0.005 mmol in terms of a titaniumatom. Then, the temperature was elevated up to 80° C., and hydrogen wassupplied at 0.3 MPa, followed by continuously supplying ethylene for 1.5hour so that the gauge pressure was 0.6 MPa. The polymerizationtemperature was maintained at 80° C.

After finishing the polymerization, an ethylene polymer was separatedfrom the n-heptane solvent by filtration, washed and dried. Afterdrying, 133.4 g of a powder-like polymer was obtained. This powder-likepolymer had MFR of 1.0 g/10 minutes and an apparent bulk density of 0.31g/ml.

Example 2 Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-1) for ethylene polymerizationwas added in an amount corresponding to 0.015 mmol in terms of atitanium atom, and then the temperature was elevated up to 80° C.;hydrogen was supplied at 0.55 MPa, and then ethylene was continuouslysupplied for 1.5 hour so that the gauge pressure was 0.6 MPa. Theresults thereof are shown in Table 1.

Example 3 Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-1) for ethylene polymerizationwas added in an amount corresponding to 0.015 mmol in terms of atitanium atom, and then the temperature was elevated up to 80° C.;hydrogen was supplied at 0.58 MPa, and then ethylene was continuouslysupplied for 1.5 hour so that the whole pressure was 0.6 MPa. Theresults thereof are shown in Table 1.

Example 4 Preparation of Solid Titanium Catalyst Component for EthylenePolymerization

A solid titanium catalyst component (I-2) for ethylene polymerizationwas obtained in the same manner as in Example 1, except that thetemperature reached in heating was changed from 110° C. to 100° C. Thecomposition thereof was such that 7.3% by weight of titanium, 14% byweight of magnesium, 58% by weight of chlorine, 1.1% by weight of anethyl alcohol residue and 9% by weight of a 2-ethylhexyl alcoholresidue.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-2) for ethylene polymerizationwas used. The results thereof are shown in Table 1.

Example 5 Preparation of Solid Titanium Catalyst Component for EthylenePolymerization

A solid titanium catalyst component (I-3) for ethylene polymerizationwas obtained in the same manner as in Example 1, except that themaintaining time at 110° C. was changed from 30 minutes to 15 minutes.The composition thereof was such that 7.1% by weight of titanium, 14% byweight of magnesium, 57% by weight of chlorine, 1.0% by weight of anethyl alcohol residue and 7.9% by weight of a 2-ethylhexyl alcoholresidue.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-3) for ethylene polymerizationwas used. The results thereof are shown in Table 1.

Example 6 Preparation of Solid Titanium Catalyst Component for EthylenePolymerization

A solid titanium catalyst component (I-4) for ethylene polymerizationwas obtained in the same manner as in Example 1, except that an amountof ethyl alcohol was changed from 0.94 g to 1.18 g and that themaintaining time at 110° C. was changed from 30 minutes to 120 minutes.The composition thereof was such that 6.7% by weight of titanium, 15% byweight of magnesium, 58% by weight of chlorine, 0.6% by weight of anethyl alcohol residue and 2.8% by weight of a 2-ethylhexyl alcoholresidue.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-4) for ethylene polymerizationwas used. The results thereof are shown in Table 1.

Example 7 Preparation of Solid Titanium Catalyst Component for EthylenePolymerization

A solid titanium catalyst component (I-5) for ethylene polymerizationwas obtained in the same manner as in Example 1, except that an amountof 2-ethylhexyl alcohol was changed from 16.3 g to 19.5 g; an amount ofethyl alcohol was changed from 0.94 g to 1.88 g; and the maintainingtime at 110° C. was changed from 30 minutes to 60 minutes. Thecomposition thereof was such that 7.0% by weight of titanium, 14% byweight of magnesium, 57% by weight of chlorine, 1.1% by weight of anethyl alcohol residue and 5.1% by weight of a 2-ethylhexyl alcoholresidue.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-5) for ethylene polymerizationwas used. The results thereof are shown in Table 1.

Example 8 Preparation of Solid Titanium Catalyst Component for EthylenePolymerization

A solid titanium catalyst component (I-6) for ethylene polymerizationwas obtained in the same manner as in Example 7, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to diisopropyltrans-cyclohexane-1,2-dicarboxylate. The composition thereof was suchthat 7.4% by weight of titanium, 14% by weight of magnesium, 57% byweight of chlorine, 1.8% by weight of an ethyl alcohol residue and 7.7%by weight of a 2-ethylhexyl alcohol residue.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-6) for ethylene polymerizationwas used. The results thereof are shown in Table 1.

Example 9 Preparation of Solid Titanium Catalyst Component for EthylenePolymerization

A solid titanium catalyst component (I-7) for ethylene polymerizationwas obtained in the same manner as in Example 1, except that an amountof 2-ethylhexyl alcohol was changed from 16.3 g to 19.5 g; an amount ofethyl alcohol was changed from 0.94 g to 2.35 g; and the maintainingtime at 110° C. was changed from 30 minutes to 60 minutes. Thecomposition thereof was such that 7.0% by weight of titanium, 15% byweight of magnesium, 58% by weight of chlorine, 1.2% by weight of anethyl alcohol residue and 4.5% by weight of a 2-ethylhexyl alcoholresidue.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-7) for ethylene polymerizationwas used. The results thereof are shown in Table 1.

Comparative Example 1 Preparation of Solid Titanium Catalyst Component

4.76 g (50 mmol) of magnesium chloride anhydrous, 28.1 ml of decane and16.3 g (125 mmol) of 2-ethylhexyl alcohol were reacted by heating at130° C. for 3 hours to prepare a homogeneous solution. Then, 0.96 g(3.75 mmol) of diisopropyl cis-cyclohexane-1,2-dicarboxylate was addedto the solution and mixed by stirring at 50° C. for further 1 hour, andthen the solution was gradually cooled down to room temperature.

A whole amount of the homogeneous solution thus obtained was dropwiseadded to 200 ml (1.8 mol) of titanium tetrachloride of 0° C. in 1 hourunder stirring. The temperature was maintained at 0° C. during dropwiseadding. After finishing addition, the mixed solution was maintained at atemperature of 0° C. for 1 hour, and then the temperature was elevatedup to 110° C. in 1 hour and 45 minutes. Thereafter, the solution wasmaintained at the temperature for 30 minutes under stirring and thenfiltrated at the same temperature to separate a solid part.

The solid part was sufficiently washed with decane of 110° C. and thenwith hexane of room temperature until the free titanium compound was notdetected to obtain a solid titanium catalyst component (8). The solidtitanium catalyst component thus obtained was stored in the form of adecane suspension, and a part thereof was dried for analysis. Thecomposition thereof was such that 6.4% by weight of titanium, 16% byweight of magnesium, 54% by weight of chlorine and 4.0% by weight of a2-ethylhexyl alcohol residue.

Polymerization

An autoclave having an inner content of 1 liter was charged with 500 mlof refined n-heptane under nitrogen atmosphere, and added thereto were0.25 mmol of triethylaluminum and a decane suspension of the solidtitanium catalyst component (8) obtained above in an amountcorresponding to 0.005 mmol in terms of a titanium atom. Then, thetemperature was elevated up to 80° C., and hydrogen was supplied at 0.3MPa, followed by continuously supplying ethylene for 1.5 hour so thatthe gauge pressure was 0.6 MPa. The polymerization temperature wasmaintained at 80° C.

After finishing the polymerization, an ethylene polymer was separatedfrom the n-heptane solvent and dried. After drying, 60.3 g of apowder-like polymer was obtained. This powder-like polymer had MFR of1.7 g/10 minutes and an apparent bulk density of 0.31 g/ml. The resultsthereof are shown in Table 1.

Comparative Example 2 Preparation of Solid Titanium Catalyst Component

7.14 g (75 mmol) of magnesium chloride anhydrous, 37.5 ml of decane and29.3 g (225 mmol) of 2-ethylhexyl alcohol were reacted by heating at130° C. for 2 hours to prepare a homogeneous solution. Then, 3.1 g (15mmol) of tetraethoxysilane was added to the solution and mixed bystirring at 50° C. for further 2 hours, and then the solution wasgradually cooled down to room temperature.

A whole amount of the homogeneous solution thus obtained was dropwiseadded to 200 ml (1.8 mol) of titanium tetrachloride maintained at 0° C.in 1 hour. After finishing addition, a temperature of the mixed solutionwas elevated up to 110° C. in 1 hour and 45 minutes. Thereafter, thesolution was maintained at the temperature for 2 hours under stirring,and then a solid part was separated at the same temperature. The solidpart was sufficiently washed with decane of 110° C. and then with hexaneof room temperature until the free titanium compound was not detected toobtain a solid titanium catalyst component (9). The solid titaniumcatalyst component thus obtained was stored in the form of a decanesuspension, and a part thereof was dried for analysis. The compositionthereof was such that 8.4% by weight of titanium, 14% by weight ofmagnesium, 58% by weight of chlorine and 4.3% by weight of a2-ethylhexyl alcohol residue.

Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 1,except that the solid titanium catalyst component (9) was used. Theresults thereof are shown in Table 1.

Comparative Example 3 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 2,except that the solid titanium catalyst component (9) was added in anamount corresponding to 0.015 mmol in terms of a titanium atom; then,the temperature was elevated up to 80° C., and hydrogen was supplied at0.55 MPa; next, ethylene was continuously supplied for 1.5 hour so thatthe gauge pressure was 0.6 MPa. The results thereof are shown in Table1.

Comparative Example 4 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 2,except that the solid titanium catalyst component (9) was added in anamount corresponding to 0.015 mmol in terms of a titanium atom; then,the temperature was elevated up to 80° C., and hydrogen was supplied at0.58 MPa; next, ethylene was continuously supplied for 1.5 hour so thatthe gauge pressure was 0.6 MPa. The results thereof are shown in Table1.

Example 10 Polymerization

An autoclave having an inner content of 1 liter was charged with 500 mlof refined n-heptane under ethylene atmosphere, and added thereto were0.25 mmol of triethylaluminum and a decane suspension of the solidtitanium catalyst component (I-1) for ethylene polymerization in anamount corresponding to 0.015 mmol in terms of a titanium atom. Then,the temperature was elevated up to 80° C., and hydrogen was supplied at0.6 MPa, followed by continuously supplying ethylene for 1.5 hour sothat the whole pressure was 0.8 MPa. The polymerization temperature wasmaintained at 80° C.

After finishing the polymerization, the autoclave was depressurized andcooled down to 65° C., and then a white powder formed was separated fromthe liquid phase part and dried. After drying, 151.1 g of a powder-likepolymer was obtained. This powder-like polymer had MFR of 37 g/10minutes. On the other hand, the solvent was removed from the separatedliquid phase part by distillation to obtain 4.8 g of a solid matter. Theresults thereof are shown in Table 2.

Example 11 Polymerization

Ethylene was polymerized in the same manner as in Example 10, exceptthat hydrogen was supplied at 0.75 MPa. The results thereof are shown inTable 2.

Example 12 Polymerization

Ethylene was polymerized in the same manner as in Example 10, exceptthat hydrogen was supplied at 0.76 MPa. The results thereof are shown inTable 2.

Example 13 Polymerization

Ethylene was polymerized in the same manner as in Example 10, exceptthat hydrogen was supplied at 0.77 MPa. The results thereof are shown inTable 2.

Comparative Example 5 Polymerization

An autoclave having an inner content of 1 liter was charged with 500 mlof refined n-heptane under ethylene atmosphere, and added thereto were0.25 mmol of triethylaluminum and a decane suspension of the solidtitanium catalyst component (8) in an amount corresponding to 0.015 mmolin terms of a titanium atom. Then, the temperature was elevated up to80° C., and hydrogen was supplied at 0.75 MPa, followed by continuouslysupplying ethylene for 1.5 hour so that the whole pressure was 0.8 MPa.The polymerization temperature was maintained at 80° C.

After finishing the polymerization, the autoclave was depressurized andcooled down to 65° C., and then a white powder formed was separated anddried. After drying, 76.7 g of a powder-like polymer was obtained. Thispowder-like polymer had MFR of 140 g/10 minutes.

On the other hand, the solvent was removed from the separated liquidphase part by distillation to obtain 4.6 g of a solid matter. Theresults thereof are shown in Table 2.

Comparative Example 6 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 5,except that hydrogen was supplied at 0.78 MPa. The results thereof areshown in Table 2.

Comparative Example 7 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 5,except that hydrogen was supplied at 0.79 MPa. The results thereof areshown in Table 2.

Example 14 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-10) was obtained in the samemanner as in Example 1, except that ethyl alcohol was changed to 1.2 g(20 mmol) of n-propanol.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-10) was used. The resultsthereof are shown in Table 3.

Example 15 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-11) was obtained in the samemanner as in Example 1, except that ethyl alcohol was changed to 1.2 g(20 mmol) of iso-propanol.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-11) was used. The resultsthereof are shown in Table 3.

Example 16 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-12) was obtained in the samemanner as in Example 1, except that ethyl alcohol was changed to 1.48 g(20 mmol) of n-butanol.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-12) was used. The resultsthereof are shown in Table 3.

Example 17 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-13) was obtained in the samemanner as in Example 1, except that ethyl alcohol was changed to 1.48 g(20 mmol) of iso-butanol.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-13) was used. The resultsthereof are shown in Table 3.

Example 18 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-14) was obtained in the samemanner as in Example 1, except that ethyl alcohol was changed to 1.76 g(20 mmol) of n-pentanol.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-14) was used. The resultsthereof are shown in Table 3.

Example 19 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-15) was obtained in the samemanner as in Example 1, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.75 g (5 mmol) ofethyl benzoate.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-15) was used. The resultsthereof are shown in Table 3.

Example 20 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-16) was obtained in the samemanner as in Example 1, except that an amount of ethyl alcohol waschanged from 0.94 g to 1.38 g (30 mmol) and that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.75 g (5 mmol) ofethyl benzoate.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-16) was used. The resultsthereof are shown in Table 3.

Example 21 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-17) was obtained in the samemanner as in Example 1, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 1.26 g (6.25 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-17) was used. The resultsthereof are shown in Table 3.

Example 22 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-18) was obtained in the samemanner as in Example 1, except that an amount of ethyl alcohol waschanged from 0.94 g to 1.38 g (30 mmol) and that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 1.26 g (6.25 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-18) was used. The resultsthereof are shown in Table 3.

Example 23 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-19) was obtained in the samemanner as in Example 1, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.96 g (3.75 mmol) ofdiisopropyl trans-cyclohexane-1,2-dicarboxylate.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-19) was used. The resultsthereof are shown in Table 3.

Example 24 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-20) was obtained in the samemanner as in Example 1, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.96 g (3.75 mmol) ofdi-n-propyl trans-cyclohexane-1,2-dicarboxylate.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-20) was used. The resultsthereof are shown in Table 3.

Comparative Example 8 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (21) was obtained in the same manneras in Comparative Example 1, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.75 g (5 mmol) ofethyl benzoate.

Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 1,except that the solid titanium catalyst component (21) was used. Theresults thereof are shown in Table 3.

Comparative Example 9 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (22) was obtained in the same manneras in Comparative Example 1, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 1.26 g (6.25 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane.

Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 1,except that the solid titanium catalyst component (22) was used. Theresults thereof are shown in Table 3.

Comparative Example 10 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (23) was obtained in the same manneras in Comparative Example 1, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.96 g (3.75 mmol) ofdi-n-propyl trans-cyclohexane-1,2-dicarboxylate.

Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 1,except that the solid titanium catalyst component (23) was used. Theresults thereof are shown in Table 3.

Example 25 Polymerization

An autoclave having an inner content of 1 liter was charged with 500 mlof refined n-heptane under ethylene atmosphere, and added thereto were0.25 mmol of triethylaluminum and a decane suspension of the solidtitanium catalyst component (I-10) in an amount corresponding to 0.015mmol in terms of a titanium atom. Then, the temperature was elevated upto 80° C., and hydrogen was supplied at 0.75 MPa, followed bycontinuously supplying ethylene for 1.5 hour so that the whole pressurewas 0.8 MPa. The polymerization temperature was maintained at 80° C.

After finishing the polymerization, the autoclave was depressurized andcooled down to 65° C., and then a white powder formed was separated fromthe liquid phase part and dried. After drying, 44.6 g of a powder-likepolymer was obtained. This powder-like polymer had MFR of 520 g/10minutes. On the other hand, the solvent was removed from the separatedliquid phase part by distillation to obtain 4.9 g of a solid matter. Theresults thereof are shown in Table 4.

Example 26 Polymerization

Ethylene was polymerized in the same manner as in Example 25, exceptthat hydrogen was supplied at 0.77 MPa. The results thereof are shown inTable 4.

Example 27 Polymerization

Ethylene was polymerized in the same manner as in Example 25, exceptthat a decane suspension of the solid titanium catalyst component (I-11)was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.76 MPa. The resultsthereof are shown in Table 4.

Example 28 Polymerization

Ethylene was polymerized in the same manner as in Example 27, exceptthat hydrogen was supplied at 0.77 MPa. The results thereof are shown inTable 4.

Example 29 Polymerization

Ethylene was polymerized in the same manner as in Example 25, exceptthat a decane suspension of the solid titanium catalyst component (I-12)was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.74 MPa. The resultsthereof are shown in Table 4.

Example 30 Polymerization

Ethylene was polymerized in the same manner as in Example 29, exceptthat hydrogen was supplied at 0.77 MPa. The results thereof are shown inTable 4.

Example 31 Polymerization

Ethylene was polymerized in the same manner as in Example 25, exceptthat a decane suspension of the solid titanium catalyst component (I-13)was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.74 MPa. The resultsthereof are shown in Table 4.

Example 32 Polymerization

Ethylene was polymerized in the same manner as in Example 31, exceptthat hydrogen was supplied at 0.77 MPa. The results thereof are shown inTable 4.

Example 33 Polymerization

Ethylene was polymerized in the same manner as in Example 25, exceptthat a decane suspension of the solid titanium catalyst component (I-15)was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.76 MPa. The resultsthereof are shown in Table 4.

Example 34 Polymerization

Ethylene was polymerized in the same manner as in Example 33, exceptthat hydrogen was supplied at 0.79 MPa. The results thereof are shown inTable 4.

Example 35 Polymerization

Ethylene was polymerized in the same manner as in Example 25, exceptthat a decane suspension of the solid titanium catalyst component (I-16)was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.77 MPa. The resultsthereof are shown in Table 4.

Example 36 Polymerization

Ethylene was polymerized in the same manner as in Example 35, exceptthat hydrogen was supplied at 0.78 MPa. The results thereof are shown inTable 4.

Example 37 Polymerization

Ethylene was polymerized in the same manner as in Example 25, exceptthat a decane suspension of the solid titanium catalyst component (I-17)was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.69 MPa. The resultsthereof are shown in Table 4.

Example 38 Polymerization

Ethylene was polymerized in the same manner as in Example 37, exceptthat hydrogen was supplied at 0.72 MPa. The results thereof are shown inTable 4.

Example 39 Polymerization

Ethylene was polymerized in the same manner as in Example 25, exceptthat a decane suspension of the solid titanium catalyst component (I-18)was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.72 MPa. The resultsthereof are shown in Table 4.

Example 40 Polymerization

Ethylene was polymerized in the same manner as in Example 39, exceptthat hydrogen was supplied at 0.76 MPa. The results thereof are shown inTable 4.

Comparative Example 11 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 5,except that a decane suspension of the solid titanium catalyst component(21) was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.77 MPa. The resultsthereof are shown in Table 4.

Comparative Example 12 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 5,except that a decane suspension of the solid titanium catalyst component(22) was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.74 MPa. The resultsthereof are shown in Table 4.

Comparative Example 13 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 5,except that hydrogen was supplied at 0.78 MPa. The results thereof areshown in Table 4.

Comparative Example 14 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 5,except that hydrogen was supplied at 0.79 MPa. The results thereof areshown in Table 4.

Example 41 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-24) was obtained in the samemanner as in Example 1, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.38 g (2.5 mmol) ofethyl benzoate and 0.51 g (2.5 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-24) was used. The resultsthereof are shown in Table 5.

Example 42 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-25) was obtained in the samemanner as in Example 1, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.50 g (3.4 mmol) ofethyl benzoate and 0.33 g (1.7 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-25) was used. The resultsthereof are shown in Table 5.

Example 43 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-26) was obtained in the samemanner as in Example 1, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.60 g (4.0 mmol) ofethyl benzoate and 0.20 g (1.0 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-26) was used. The resultsthereof are shown in Table 5.

Example 44 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-27) was obtained in the samemanner as in Example 1, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.64 g (4.3 mmol) ofethyl benzoate and 0.15 g (0.8 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-27) was used. The resultsthereof are shown in Table 5.

Example 45 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-28) was obtained in the samemanner as in Example 1, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.68 g (4.5 mmol) ofethyl benzoate and 0.10 g (0.5 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-28) was used. The resultsthereof are shown in Table 5.

Example 46 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-29) was obtained in the samemanner as in Example 1, except that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.71 g (4.8 mmol) ofethyl benzoate and 0.05 g (0.3 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-29) was used. The resultsthereof are shown in Table 5.

Example 47 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-30) was obtained in the samemanner as in Example 1, except that an amount of ethyl alcohol waschanged from 0.94 g to 1.38 g (30 mmol) and that diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.71 g (4.8 mmol) ofethyl benzoate and 0.05 g (0.3 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-30) was used. The resultsthereof are shown in Table 5.

Example 48 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-31) was obtained in the samemanner as in Example 1, except that an amount of ethyl alcohol waschanged from 0.94 g to 1.38 g (30 mmol); diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.68 g (4.5 mmol) ofethyl benzoate and 0.10 g (0.5 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane; and the condition of 30minutes under stirring after elevating the temperature up to 110° C. wasshortened to 15 minutes.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-31) was used. The resultsthereof are shown in Table 5.

Example 49 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-32) was obtained in the samemanner as in Example 1, except that an amount of ethyl alcohol waschanged from 0.94 g to 1.38 g (30 mmol); diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.68 g (4.5 mmol) ofethyl benzoate and 0.10 g (0.5 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane; and the condition of 30minutes under stirring after elevating the temperature up to 110° C. waschanged to maintaining stirring for 30 minutes after elevating thetemperature up to 100° C.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-32) was used. The resultsthereof are shown in Table 5.

Example 50 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-33) was obtained in the samemanner as in Example 1, except that an amount of ethyl alcohol waschanged from 0.94 g to 1.38 g (30 mmol); diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.68 g (4.5 mmol) ofethyl benzoate and 0.10 g (0.5 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane; and the condition of 30minutes under stirring after elevating the temperature up to 110° C. waschanged to maintaining stirring for 15 minutes after elevating thetemperature up to 100° C.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-33) was used. The resultsthereof are shown in Table 5.

Example 51 Preparation of Solid Titanium Catalyst Component

A solid titanium catalyst component (I-34) was obtained in the samemanner as in Example 1, except that an amount of ethyl alcohol waschanged from 0.94 g to 1.38 g (30 mmol); diisopropylcis-cyclohexane-1,2-dicarboxylate was changed to 0.68 g (4.5 mmol) ofethyl benzoate and 0.10 g (0.5 mmol) of2-isopropyl-2-isobutyl-1,3-dimethoxypropane; and the condition of 30minutes under stirring after elevating the temperature up to 110° C. waschanged to maintaining stirring for 15 minutes after elevating thetemperature up to 90° C.

Polymerization

Ethylene was polymerized in the same manner as in Example 1, except thatthe solid titanium catalyst component (I-34) was used. The resultsthereof are shown in Table 5.

Example 52 Polymerization

An autoclave having an inner content of 1 liter was charged with 500 mlof refined n-heptane under ethylene atmosphere, and added thereto were0.25 mmol of triethylaluminum and a decane suspension of the solidtitanium catalyst component (I-24) in an amount corresponding to 0.015mmol in terms of a titanium atom. Then, the temperature was elevated upto 80° C., and hydrogen was supplied at 0.76 MPa, followed bycontinuously supplying ethylene for 1.5 hour so that the whole pressurewas 0.8 MPa. The polymerization temperature was maintained at 80° C.

After finishing the polymerization, the autoclave was depressurized andcooled down to 65° C., and then a white powder formed was separated fromthe liquid phase part and dried. After drying, 53.8 g of a powder-likepolymer was obtained. This powder-like polymer had MFR of 950 g/10minutes. On the other hand, the solvent was removed from the separatedliquid phase part by distillation to obtain 5.7 g of a solid matter. Theresults thereof are shown in Table 6.

Example 53 Polymerization

Ethylene was polymerized in the same manner as in Example 52, exceptthat hydrogen was supplied at 0.74 MPa. The results thereof are shown inTable 6.

Example 54 Polymerization

Ethylene was polymerized in the same manner as in Example 52, exceptthat hydrogen was supplied at 0.72 MPa. The results thereof are shown inTable 6.

Example 55 Polymerization

An autoclave having an inner content of 1 liter was charged with 500 mlof refined n-heptane under ethylene atmosphere, and added thereto were0.25 mmol of triethylaluminum and a decane suspension of the solidtitanium catalyst component (I-25) in an amount corresponding to 0.015mmol in terms of a titanium atom. Then, the temperature was elevated upto 80° C., and hydrogen was supplied at 0.76 MPa, followed bycontinuously supplying ethylene for 1.5 hour so that the whole pressurewas 0.8 MPa. The polymerization temperature was maintained at 80° C.

After finishing the polymerization, the autoclave was depressurized andcooled down to 65° C., and then a white powder formed was separated fromthe liquid phase part and dried. After drying, 54.7 g of a powder-likepolymer was obtained. This powder-like polymer had MFR of 670 g/10minutes. On the other hand, the solvent was removed from the separatedliquid phase part by distillation to obtain 5.7 g of a solid matter. Theresults thereof are shown in Table 6.

Example 56 Polymerization

Ethylene was polymerized in the same manner as in Example 55, exceptthat hydrogen was supplied at 0.74 MPa. The results thereof are shown inTable 6.

Example 57 Polymerization

Ethylene was polymerized in the same manner as in Example 55, exceptthat hydrogen was supplied at 0.72 MPa. The results thereof are shown inTable 6.

Example 58 Polymerization

An autoclave having an inner content of 1 liter was charged with 500 mlof refined n-heptane under ethylene atmosphere, and added thereto were0.25 mmol of triethylaluminum and a decane suspension of the solidtitanium catalyst component (I-26) in an amount corresponding to 0.015mmol in terms of a titanium atom. Then, the temperature was elevated upto 80° C., and hydrogen was supplied at 0.76 MPa, followed bycontinuously supplying ethylene for 1.5 hour so that the whole pressurewas 0.8 MPa. The polymerization temperature was maintained at 80° C.

After finishing the polymerization, the autoclave was depressurized andcooled down to 65° C., and then a white powder formed was separated fromthe liquid phase part and dried. After drying, 40.1 g of a powder-likepolymer was obtained. This powder-like polymer had MFR of 640 g/10minutes. On the other hand, the solvent was removed from the separatedliquid phase part by distillation to obtain 4.8 g of a solid matter. Theresults thereof are shown in Table 6.

Example 59 Polymerization

Ethylene was polymerized in the same manner as in Example 58, exceptthat hydrogen was supplied at 0.74 MPa. The results thereof are shown inTable 6.

Example 60 Polymerization

Ethylene was polymerized in the same manner as in Example 58, exceptthat hydrogen was supplied at 0.72 MPa. The results thereof are shown inTable 6.

Example 61 Polymerization

An autoclave having an inner content of 1 liter was charged with 500 mlof refined n-heptane under ethylene atmosphere, and added thereto were0.25 mmol of triethylaluminum and a decane suspension of the solidtitanium catalyst component (I-27) in an amount corresponding to 0.015mmol in terms of a titanium atom. Then, the temperature was elevated upto 80° C., and hydrogen was supplied at 0.76 MPa, followed bycontinuously supplying ethylene for 1.5 hour so that the whole pressurewas 0.8 MPa. The polymerization temperature was maintained at 80° C.

After finishing the polymerization, the autoclave was depressurized andcooled down to 65° C., and then a white powder formed was separated fromthe liquid phase part and dried. After drying, 51.2 g of a powder-likepolymer was obtained. This powder-like polymer had MFR of 950 g/10minutes. On the other hand, the solvent was removed from the separatedliquid phase part by distillation to obtain 5.3 g of a solid matter. Theresults thereof are shown in Table 6.

Example 62 Polymerization

Ethylene was polymerized in the same manner as in Example 61, exceptthat hydrogen was supplied at 0.74 MPa. The results thereof are shown inTable 6.

Example 63 Polymerization

Ethylene was polymerized in the same manner as in Example 61, exceptthat hydrogen was supplied at 0.72 MPa. The results thereof are shown inTable 6.

Example 64 Polymerization

An autoclave having an inner content of 1 liter was charged with 500 mlof refined n-heptane under ethylene atmosphere, and added thereto were0.25 mmol of triethylaluminum and a decane suspension of the solidtitanium catalyst component (I-28) in an amount corresponding to 0.015mmol in terms of a titanium atom. Then, the temperature was elevated upto 80° C., and hydrogen was supplied at 0.76 MPa, followed bycontinuously supplying ethylene for 1.5 hour so that the whole pressurewas 0.8 MPa. The polymerization temperature was maintained at 80° C.

After finishing the polymerization, the autoclave was depressurized andcooled down to 65° C., and then a white powder formed was separated fromthe liquid phase part and dried. After drying, 38.7 g of a powder-likepolymer was obtained. This powder-like polymer had MFR of 860 g/10minutes. On the other hand, the solvent was removed from the separatedliquid phase part by distillation to obtain 5.3 g of a solid matter. Theresults thereof are shown in Table 6.

Example 65 Polymerization

Ethylene was polymerized in the same manner as in Example 64, exceptthat hydrogen was supplied at 0.74 MPa. The results thereof are shown inTable 6.

Example 66 Polymerization

An autoclave having an inner content of 1 liter was charged with 500 mlof refined n-heptane under ethylene atmosphere, and added thereto were0.25 mmol of triethylaluminum and a decane suspension of the solidtitanium catalyst component (I-29) in an amount corresponding to 0.015mmol in terms of a titanium atom. Then, the temperature was elevated upto 80° C., and hydrogen was supplied at 0.76 MPa, followed bycontinuously supplying ethylene for 1.5 hour so that the whole pressurewas 0.8 MPa. The polymerization temperature was maintained at 80° C.

After finishing the polymerization, the autoclave was depressurized andcooled down to 65° C., and then a white powder formed was separated fromthe liquid phase part and dried. After drying, 46.5 g of a powder-likepolymer was obtained. This powder-like polymer had MFR of 600 g/10minutes. On the other hand, the solvent was removed from the separatedliquid phase part by distillation to obtain 5.6 g of a solid matter. Theresults thereof are shown in Table 6.

Example 67 Polymerization

Ethylene was polymerized in the same manner as in Example 66, exceptthat hydrogen was supplied at 0.74 MPa. The results thereof are shown inTable 6.

Example 68 Polymerization

An autoclave having an inner content of 1 liter was charged with 500 mlof refined n-heptane under ethylene atmosphere, and added thereto were0.25 mmol of triethylaluminum and a decane suspension of the solidtitanium catalyst component (I-30) in an amount corresponding to 0.015mmol in terms of a titanium atom. Then, the temperature was elevated upto 80° C., and hydrogen was supplied at 0.76 MPa, followed bycontinuously supplying ethylene for 1.5 hour so that the whole pressurewas 0.8 MPa. The polymerization temperature was maintained at 80° C.

After finishing the polymerization, the autoclave was depressurized andcooled down to 65° C., and then a white powder formed was separated fromthe liquid phase part and dried. After drying, 82.2 g of a powder-likepolymer was obtained. This powder-like polymer had MFR of 410 g/10minutes. On the other hand, the solvent was removed from the separatedliquid phase part by distillation to obtain 6.3 g of a solid matter. Theresults thereof are shown in Table 6.

Example 69 Polymerization

Ethylene was polymerized in the same manner as in Example 68, exceptthat hydrogen was supplied at 0.74 MPa. The results thereof are shown inTable 6.

Example 70 Polymerization

An autoclave having an inner content of 1 liter was charged with 500 mlof refined n-heptane under ethylene atmosphere, and added thereto were0.25 mmol of triethylaluminum and a decane suspension of the solidtitanium catalyst component (I-31) in an amount corresponding to 0.015mmol in terms of a titanium atom. Then, the temperature was elevated upto 80° C., and hydrogen was supplied at 0.78 MPa, followed bycontinuously supplying ethylene for 1.5 hour so that the whole pressurewas 0.8 MPa. The polymerization temperature was maintained at 80° C.

After finishing the polymerization, the autoclave was depressurized andcooled down to 65° C., and then a white powder formed was separated fromthe liquid phase part and dried. After drying, 61.3 g of a powder-likepolymer was obtained. This powder-like polymer had MFR of 640 g/10minutes. On the other hand, the solvent was removed from the separatedliquid phase part by distillation to obtain 4.6 g of a solid matter. Theresults thereof are shown in Table 6.

Example 71 Polymerization

Ethylene was polymerized in the same manner as in Example 70, exceptthat hydrogen was supplied at 0.79 MPa. The results thereof are shown inTable 6.

Comparative Example 15 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 5,except that a decane suspension of the solid titanium catalyst component(9) was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.72 MPa. The resultsthereof are shown in Table 7.

Comparative Example 16 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 5,except that a decane suspension of the solid titanium catalyst component(9) was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.75 MPa. The resultsthereof are shown in Table 7.

Comparative Example 17 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 5,except that a decane suspension of the solid titanium catalyst component(9) was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.76 MPa. The resultsthereof are shown in Table 7.

Comparative Example 18 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 5,except that a decane suspension of the solid titanium catalyst component(9) was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.77 MPa. The resultsthereof are shown in Table 7.

Comparative Example 19 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 5,except that a decane suspension of the solid titanium catalyst component(9) was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.78 MPa. The resultsthereof are shown in Table 7.

Comparative Example 20 Polymerization

Ethylene was polymerized in the same manner as in Comparative Example 5,except that a decane suspension of the solid titanium catalyst component(9) was added in an amount corresponding to 0.015 mmol in terms of atitanium atom and that hydrogen was supplied at 0.79 MPa. The resultsthereof are shown in Table 7.

TABLE 1 Polymerization results Particle Activity size MgCl₂-solubilizingagent Hy- kg-PE/ distri- Kind ROH dro- g- MFR bution of EHA/MgCl₂Electron (a)/MgCl₂ Electron gen Yield mmol- cata- g/10 BD <75 μm cata-(m.r.) donor (a) (m.r.) ROH/EHA donor (B) MPa g Ti lyst min g/ml weight% lyst Example 1 2.5 EtOH 0.4 0.16 Diisopropyl 0.3 133.4 26.7 39.0 1.00.31 4.3 I-1 Example 2 2.5 0.4 0.16 cis-cyclo- 0.55 42.4 2.8 4.1 3700.33 — Example 3 2.5 0.4 0.16 hexane-1,2- 0.58 26.9 1.8 2.6 870 0.32 —Example 4 2.5 0.4 0.16 dicarboxylate 0.3 115.0 23.0 35.1 1.4 0.30 3.5I-2 Example 5 2.5 0.4 0.16 0.3 108.1 21.6 32.0 2.3 0.28 3.8 I-3 Example6 2.5 0.5 0.20 0.3 88.8 17.8 24.8 1.4 0.25 12.3 I-4 Example 7 3.0 0.80.27 0.3 106.9 21.4 31.2 1.4 0.27 3.1 I-5 Example 8 3.0 0.8 0.27Diisopropyl 0.3 119.0 23.8 36.8 1.6 0.26 1.8 I-6 trans-cyclo-hexane-1,2- dicarboxylate Example 9 3.0 1.0 0.33 Diisopropyl 0.3 105.221.0 30.7 1.7 0.25 8.4 I-7 cis-cyclo- hexane-1,2- dicarboxylate Compar-2.5 — — — Diisopropyl 0.3 60.3 12.1 16.1 1.7 0.31 16.2 8 ativecis-cyclo- Example 1 hexane-1,2- dicarboxylate Compar- 3.0 — — — Tetra-0.3 121.5 24.3 42.6 3.0 0.31 3.2 9 ative ethoxysilane Example 2 Compar-3.0 — — — 0.55 75.3 5.6 8.8 130 0.31 — ative Example 3 Compar- 3.0 — — —0.58 34.5 2.3 3.6 470 0.31 — ative Example 4 EHA: 2-ethylhexyl alcohol,EtOH: ethyl alcohol

TABLE 2 Polymerization results Activity Solvent- kg-PE/ soluble KindMgCl₂-solubilizing agent Hydro- g- MFR component of EHA/MgCl₂ ElectronROH(a)/MgCl₂ Electron gen Yield mmol- cata- g/10 [η] ratio cata- (m.r.)donor (a) (m.r.) ROH/EHA donor (B) MPa g Ti lyst min dl/g % lyst Example10 2.5 EtOH 0.4 0.16 Diisopropyl 0.60 151.1 10.2 15.0 37 0.98 3.1 I-1Example 11 2.5 0.4 0.16 cis-cyclo- 0.75 71.4 5.0 7.3 265 0.66 6.2Example 12 2.5 0.4 0.16 hexane-1,2- 0.76 68.1 4.8 7.0 340 0.63 7.4Example 13 2.5 0.4 0.16 dicarboxylate 0.77 53.8 3.8 5.5 400 0.61 7.9Compar- 2.5 — — — 0.75 76.7 5.3 9.1 140 0.75 5.7 8 ative Example 5Compar- 2.5 — — — Diisopropyl 0.78 49.5 3.5 5.9 270 0.66 8.0 ativecis-cyclo- Example 6 hexane-1,2- Compar- 2.5 — — — dicarboxylate 0.7942.0 3.0 5.1 320 0.63 8.9 ative Example 7

TABLE 3 Polymerization results Activity Particle Contents of electrondonors (a) (b) kg-PE/ size Kind ROH Hydro- g- MFR distribution ofEHA/MgCl₂ Electron (a)/MgCl₂ Electron gen Yield mmol- cata- g/10 BD <75μm cata- (m.r.) donor (a) (m.r.) ROH/EHA donor (B) MPa g Ti lyst ming/ml weight % lyst Example 14 2.5 n-Propanol 0.4 0.16 Diisopropyl 0.3098.3 19.7 27.5 1.4 0.33 2.8 I-10 Example 15 2.5 iso-Propanol 0.4 0.16cis-cyclo- 0.30 76.1 15.2 22.9 1.5 0.32 1.4 I-11 Example 16 2.5n-Butanol 0.4 0.16 hexane-1,2- 0.30 68.2 13.6 18.5 1.7 0.32 0.6 I-12Example 17 2.5 iso-Butanol 0.4 0.16 dicarboxylate 0.30 67.8 13.6 16.72.2 0.31 1.6 I-13 Example 18 2.5 n-Pentanol 0.4 0.16 0.30 65.3 13.2 16.22.4 0.31 1.4 I-14 Example 19 2.5 EtOH 0.4 0.16 Ethyl benzoate 0.30 109.621.9 24.3 3.5 0.34 0.8 I-15 Example 20 2.5 0.6 0.24 0.30 132.8 26.6 28.33.3 0.31 1.0 I-16 Example 21 2.5 0.4 0.16 2-Isopropyl-2- 0.30 124.5 24.926.5 3.1 0.31 4.8 Example 22 2.5 0.6 0.24 isobutyl-1,3- 0.30 134.0 26.831.3 4.1 0.26 13.2 I-18 dimethoxy- propane Example 23 2.5 0.4 0.16Diisopropyl 0.30 108.1 21.6 33.0 1.6 0.27 0.4 I-19 trans-cyclo-hexane-1,2- dicarboxylate Example 24 2.5 0.4 0.16 Di-n-propyl 0.30 84.817.0 18.8 1.7 0.32 4.4 I-20 trans-cyclo- hexane-1,2- dicarboxylateCompar- 2.5 — — — Ethyl benzoate 0.30 34.0 6.8 6.7 2.6 0.28 8.4 21 ativeExample 8 Compar- 2.5 — — — 2-Isopropyl-2- 0.30 53.2 10.6 11.6 0.3 9.205.6 22 ative isobutyl-1,3- Example 9 dimethoxy- propane Compar- 2.5 — —— Di-n-propyl 0.30 26.0 5.2 6.6 2.7 0.30 0.6 23 ative trans-cyclo-Example 10 hexane-1,2- dicarboxylate

TABLE 4 Contents of electron donors (a) (b) Polymerization resultsEHA/MgCl₂ Electron ROH(a)/MgCl₂ Electron Hydrogen Yield (m.r.) donor (a)(m.r.) ROH/EHA donor (B) MPa g Example 25 2.5 n-Propanol 0.4 0.16Diisopropyl cis- 0.75 44.6 Example 26 2.5 0.4 0.16 cyclohexane-1,2 0.7720.9 Example 27 2.5 iso-Propanol 0.4 0.16 dicarboxylate 0.76 32.3Example 28 2.5 0.4 0.16 0.77 16.0 Example 29 2.5 0.4 0.16 0.74 34.1Example 30 2.5 n-Butanol 0.4 0.16 0.77 30.7 Example 31 2.5 iso-Butanol0.4 0.16 0.74 30.4 Example 32 2.5 0.4 0.16 0.77 19.0 Example 33 2.5 EtOH0.4 0.16 Ethyl benzoate 0.76 45.0 Example 34 2.5 0.4 0.16 0.79 17.7Example 35 2.5 0.6 0.24 0.77 73.9 Example 36 2.5 0.6 0.24 0.78 46.8Example 37 2.5 0.4 0.16 2-Isopropyl-2- 0.69 101.6 Example 38 2.5 0.40.16 isobutyl-1,3- 0.72 84.1 Example 39 2.5 0.6 0.24 dimethoxypropane0.72 97.8 Example 40 2.5 0.6 0.24 0.76 45.7 Comparative 2.5 — — — Ethylbenzoate 0.77 3.6 Example 11 Comparative 2.5 — — — 2-Isopropyl-2- 0.7432.0 Example 12 isobutyl-1,3- dimethoxypropane Comparative 2.5 — — —Diisopropyl cis- 0.78 40.3 Example 13 cyclohexane-1,2 Comparative 2.5 —— — dicarboxylate 0.79 22.7 Example 14 Polymerization resultsSolvent-soluble Activity kg-PE/ MFR [η] component ratio Kind of mmol-Tig-catalyst g/10 min dl/g % catalyst Example 25 3.0 4.2 520 0.57 11.1I-10 Example 26 1.4 1.9 >800 0.51 13.8 Example 27 2.2 3.2 530 0.57 11.5I-11 Example 28 1.1 1.6 >800 0.48 16.3 Example 29 2.3 3.1 610 0.55 12.4I-12 Example 30 2.0 2.8 740 0.54 13.4 Example 31 2.0 2.5 530 0.56 9.9I-13 Example 32 1.3 1.6 >800 0.50 14.8 Example 33 3.0 3.3 670 0.55 14.2I-15 Example 34 1.2 1.3 >800 0.46 27.4 Example 35 4.9 5.2 440 0.61 11.6I-16 Example 36 3.1 3.3 650 0.56 14.5 Example 37 6.8 7.2 420 0.58 6.1I-17 Example 38 5.6 6.0 570 0.55 7.4 Example 39 6.5 7.1 600 0.55 5.8I-18 Example 40 3.0 3.3 >800 0.46 9.5 Comparative 0.2 0.2 >800 0.50 31.521 Example 11 Comparative 2.1 2.3 620 0.55 10.7 22 Example 12Comparative 2.7 3.9 480 0.58 12.6  8 Example 13 Comparative 1.5 2.2 >8000.49 19.2 Example 14

TABLE 5 Contents of electron donors (a) (b) EHA/MgCl₂ ElectronROH(a)/MgCl₂ Electron (B1)/MgCl₂ Electron (B2)/MgCl₂ (m.r.) donor (a)(m.r.) ROH/EHA donor (B1) (m.r.) donor (B2) (m.r.) Example 41 2.5 EtOH0.4 0.16 Ethyl 0.05 2-Isopropyl-2- 0.05 Example 42 2.5 0.4 0.16 benzoate0.067 isobutyl-1,3- 0.03 Example 43 2.5 0.4 0.16 0.08 dimethoxypropane0.02 Example 44 2.5 0.4 0.16 0.085 0.015 Example 45 2.5 0.4 0.16 0.090.01 Example 46 2.5 0.4 0.16 0.095 0.005 Example 47 2.5 0.6 0.24 0.0950.005 Example 48 2.5 0.6 0.24 0.09 0.01 Example 49 2.5 0.6 0.24 0.090.01 Example 50 2.5 0.6 0.24 0.09 0.01 Example 51 2.5 0.6 0.24 0.09 0.01Polymerization results Particle size distribu- Hydrogen Yield Activitykg-PE/ MFR BD tion <75 μm Kind of MPa g mmol-Ti g-catalyst g/10 min g/mlweight % catalyst Example 41 0.30 125.8 25.2 27.8 3.1 0.32 2.4 I-24Example 42 0.30 121.7 24.3 27.9 3.8 0.32 1.0 I-25 Example 43 0.30 106.921.4 23.7 3.8 0.34 1.2 I-26 Example 44 0.30 129.5 25.9 27.6 3.5 0.33 0.2I-27 Example 45 0.30 113.6 22.7 24.7 2.8 0.34 0.4 I-28 Example 46 0.30116.5 23.3 26.3 2.5 0.32 0.8 I-29 Example 47 0.30 148.0 29.6 33.4 2.50.30 0.2 I-30 Example 48 0.30 149.9 30.0 36.3 3.1 0.30 2.6 I-31 Example49 0.30 135.2 27.0 36.1 2.6 0.30 1.2 I-32 Example 50 0.30 125.3 25.136.1 2.3 0.30 0.4 I-33 Example 51 0.30 118.8 23.8 38.7 2.1 0.29 1.2 I-34

TABLE 6 Contents of electron donors (a) (b) EHA/MgCl₂ ElectronROH(a)/MgCl₂ Electron (B1)/MgCl₂ Electron (B2)/MgCl₂ (m.r.) donor (a)(m.r.) ROH/EHA donor (B1) (m.r.) donor (B2) (m.r.) Example 52 2.5 EtOH0.4 0.16 Ethyl 0.05 2-Isopropyl-2- 0.05 Example 53 2.5 0.4 0.16 benzoate0.05 isobutyl-1,3- 0.05 Example 54 2.5 0.4 0.16 0.05 dimethoxypropane0.05 Example 55 2.5 0.4 0.16 0.067 0.03 Example 56 2.5 0.4 0.16 0.0670.03 Example 57 2.5 0.4 0.16 0.067 0.03 Example 58 2.5 0.4 0.16 0.080.02 Example 59 2.5 0.4 0.16 0.08 0.02 Example 60 2.5 0.4 0.16 0.08 0.02Example 61 2.5 0.4 0.16 0.085 0.015 Example 62 2.5 0.4 0.16 0.085 0.015Example 63 2.5 0.4 0.16 0.085 0.015 Example 64 2.5 0.4 0.16 0.09 0.01Example 65 2.5 0.4 0.16 0.09 0.01 Example 66 2.5 0.4 0.16 0.095 0.005Example 67 2.5 0.4 0.16 0.095 0.005 Example 68 2.5 0.6 0.24 0.095 0.005Example 69 2.5 0.6 0.24 0.095 0.005 Example 70 2.5 0.6 0.24 0.09 0.01Example 71 2.5 0.6 0.24 0.09 0.01 Polymerization results Solvent-solubleHydrogen Yield Activity kg-PE/ MFR [η] component ratio Kind of MPa gmmol-Ti g-catalyst g/10 min dl/g % catalyst Example 52 0.76 53.8 4.0 3.6950 0.51 10.6 I-24 Example 53 0.74 65.7 4.8 4.4 650 0.55 8.6 Example 540.72 93.1 6.9 6.2 350 0.60 6.4 Example 55 0.76 54.7 4.2 3.6 670 0.5510.5 I-25 Example 56 0.74 60.4 4.6 4.0 600 0.55 9.7 Example 57 0.72 76.55.9 5.1 380 0.59 7.8 Example 58 0.76 40.1 3.0 2.7 640 0.55 12.0 I-26Example 59 0.74 52.8 3.9 3.5 580 0.56 9.3 Example 60 0.72 70.7 5.2 4.7320 0.64 6.8 Example 61 0.76 51.2 3.6 3.4 950 0.51 10.3 I-27 Example 620.74 53.8 3.8 3.6 680 0.55 8.7 Example 63 0.72 67.8 4.8 4.5 360 0.62 7.3Example 64 0.76 38.7 2.8 2.6 860 0.50 13.6 I-28 Example 65 0.74 66.6 4.84.4 360 0.62 8.1 Example 66 0.76 46.5 3.5 3.1 600 0.56 12.0 I-29 Example67 0.74 65.5 4.9 4.4 340 0.55 8.5 Example 68 0.76 82.2 5.9 5.5 410 0.607.6 I-30 Example 69 0.74 90.2 6.5 6.0 360 0.62 7.5 Example 70 0.78 61.35.0 4.1 640 0.55 7.5 I-31 Example 71 0.79 50.1 4.0 3.3 840 0.52 8.1

TABLE 7 Polymerization results Solvent-soluble Hydrogen Yield Activitykg-PE/ MFR [η] component ratio Kind of MPa g mmol-Ti g-catalyst g/10 mindl/g % catalyst Comparative 0.72 71.1 8.1 4.7 230 0.67 8.3 9 Example 15Comparative 0.75 36.5 6.3 3.7 300 0.64 10.3 9 Example 16 Comparative0.76 46.6 5.3 3.1 390 0.60 12.3 9 Example 17 Comparative 0.77 21.9 3.72.2 680 0.56 15.9 9 Example 18 Comparative 0.78 22.4 3.8 2.2 700 0.5515.6 9 Example 19 Comparative 0.79 20.6 2.3 1.4 1500 0.46 24.1 9 Example20

INDUSTRIAL APPLICABILITY

It can be found from the results that the ethylene polymerizationcatalysts of the present invention have the excellent characteristics ofa high polymerization activity, a high hydrogen response for controllinga molecular weight and a low content of solvent-soluble components.

The invention claimed is:
 1. A solid titanium catalyst component (I)that comprises magnesium, titanium, and a halogen for ethylenepolymerization, wherein the catalyst component (I) is obtained bybringing a liquid magnesium compound (A) comprising a magnesiumcompound, an electron donor (a) having 1 to 5 carbon atoms and anelectron donor (b) having 6 to 30 carbon atoms into contact with aliquid titanium compound (C) under the presence of an electron donor(B), wherein bringing the liquid magnesium compound (A) into contactwith the liquid titanium compound (C) under the presence of the electrondonor (B) is performed by bringing a mixture into contact with theliquid titanium compound (C) wherein the mixture is a liquid obtained bymixing in advance the liquid magnesium compound (A) with the electrondonor (B), wherein the electron donor (B) is a mixture of a benzoic acidester having 8 to 18 carbon atoms and a diether compound represented bythe following formula (3):

wherein in formula (3), m represents an integer of 1 to 10; R¹¹, R¹² andR³¹ to R³⁶ each are independently a hydrogen atom or a substituenthaving at least one element selected from carbon, hydrogen, oxygen,fluorine, chlorine, bromine, iodine, nitrogen, sulfur, phosphorus, boronand silicon; any one of R¹¹, R¹² and R³¹ to R³⁶ may be linked togetherto form a ring other than a benzene ring, and a main chain may containan atom other than carbon, wherein a molar ratio between the electrondonor (b) and a titanium atom each contained in the solid titaniumcatalyst component (I) is 0.2 to
 10. 2. The solid titanium catalystcomponent (I) for ethylene polymerization as described in claim 1,wherein the molar ratio ((a)/(b)) of the used amount of the electrondonor (a) to the used amount of the electron donor (b) is less than 1,and the electron donor (a) and the electron donor (b) are heteroatom-containing compounds excluding cyclic ether compounds.
 3. The solidtitanium catalyst component (I) for ethylene polymerization as describedin claim 1, wherein the electron donor (a) is an alcohol having 1 to 5carbon atoms, and the electron donor (b) is an alcohol having 6 to 12carbon atoms.
 4. An ethylene polymerization catalyst comprising thesolid titanium catalyst component (I) for ethylene polymerization asdescribed in claim 1 and an organic metal compound catalyst component(II).
 5. An ethylene polymerization method comprising homopolymerizingethylene or copolymerizing ethylene with other olefins in the presenceof the ethylene polymerization catalyst in claim
 4. 6. The solidtitanium catalyst component (I) for ethylene polymerization of claim 1,wherein a molar ratio between the electron donor (a) and a titanium atomeach contained in the solid titanium catalyst component (I) is 0.01 to10.
 7. A method of producing a solid titanium catalyst component (I) forethylene polymerization, comprising: mixing a liquid magnesium compound(A) comprising a magnesium compound, an electron donor (a) having 1 to 5carbon atoms and an electron donor (b) having 6 to 30 carbon atoms withan electron donor (B) to obtain a liquid, and bringing the liquid intocontact with a liquid titanium compound (C), wherein the electron donor(B) is a mixture of a benzoic acid ester having 8 to 18 carbon atoms anda diether compound represented by the following formula (3):

wherein in formula (3), m represents an integer of 1 to 10; R¹¹, R¹² andR³¹ to R³⁶ each are independently a hydrogen atom or a substituenthaving at least one element selected from carbon, hydrogen, oxygen,fluorine, chlorine, bromine, iodine, nitrogen, sulfur, phosphorus, boronand silicon; any one of R¹¹, R¹² and R³¹ to R³⁶ may be linked togetherto form a ring other than a benzene ring, and a main chain may containan atom other than carbon, wherein a molar ratio between the electrondonor (b) and a titanium atom each contained in the solid titaniumcatalyst component (I) is 0.2 to 10, wherein the solid titanium catalystcomponent (I) comprises titanium, magnesium and a halogen.
 8. The methodas described in claim 7, wherein the molar ratio ((a)/(b)) of the usedamount of the electron donor (a) to the used amount of the electrondonor (b) is less than 1, and the electron donor (a) and the electrondonor (b) are hetero atom-containing compounds excluding cyclic ethercompounds.
 9. The method as described in claim 7, wherein the electrondonor (a) is an alcohol having 1 to 5 carbon atoms, and the electrondonor (b) is an alcohol having 6 to 12 carbon atoms.
 10. The method asdescribed in claim 7, a molar ratio between the electron donor (a) and atitanium atom each contained in the solid titanium catalyst component(I) is 0.01 to
 10. 11. A method of producing an ethylene polymerizationcatalyst, comprising producing a solid titanium catalyst component (1)for ethylene polymerization according to the method of claim 7, andcontacting the solid titanium catalyst component (I) with an organicmetal compound catalyst component (II).
 12. An ethylene polymerizationmethod comprising producing an ethylene polymerization catalyst asdescribed in claim 11, and homopolymerizing ethylene or copolymerizingethylene with other olefins in the presence of the ethylenepolymerization catalyst.